I have found at least one album, which after saving normally and stuff, when you click the "Submit Acoustic Features" button, the first time, it doesn't put the green checkmarks in the AcoustBrainz Status column... and then when you click the "Submit Acoustic Features" button a second time, it will process a few files and then crash Picard.

I've managed to crash Picard twice in a row now. So, I think this is reproducible. The second time I was running Picard in debug mode, and this is the last few seconds of output:

... thousands of lines of debug output snipped ...

D: 17:53:17,774 webservice/ratecontrol.get_delay_to_next_request:121: ('acousticbrainz.org', 443): Last request was 993 ms ago, waiting 7 ms before starting another one
D: 17:53:17,783 webservice/ratecontrol.get_delay_to_next_request:118: ('acousticbrainz.org', 443): Last request was 1001 ms ago, starting another one
D: 17:53:17,783 webservice/ratecontrol.increment_requests:138: ('acousticbrainz.org', 443): Incrementing requests to: 1
D: 17:53:18,050 webservice/ratecontrol.decrement_requests:146: ('acousticbrainz.org', 443): Decrementing requests to: 0
D: 17:53:18,050 webservice/_init_._handle_reply:540: Received reply for https://acousticbrainz.org:443/47520382-aae0-48d1-9e82-e8ce48d3e0b8/low-level: HTTP 200 (OK)
D: 17:53:18,051 webservice/_init_._handle_reply:553: Response received: {'message': 'ok'}
D: 17:53:18,051 acousticbrainz/_init.submit_features_callback:286: AcousticBrainz features were successfully submitted: /Volumes/out5/2022_03_14/SynthwaveVaporwave/Zimmermann, Peter/Z I M M E R M A N I A (Vol. I)/Peter Zimmermann - Z I M M E R M A N I A (Vol. I) - 04>
D: 17:53:18,052 file.update:707: Updating file <FLACFile "Peter Zimmermann - Z I M M E R M A N I A (Vol. I) - 04 It's Fresh, It's Cool, It's True.flac">
D: 17:53:18,054 webservice/ratecontrol._out_of_backoff:222: ('acousticbrainz.org', 443): oobackoff; delay: 1000ms -> 1000ms; slow start; window size 327.000 -> 328.000
D: 17:53:18,124 webservice/ratecontrol.get_delay_to_next_request:121: ('acousticbrainz.org', 443): Last request was 341 ms ago, waiting 659 ms before starting another one
D: 17:53:18,635 acousticbrainz/_init_.get:94: ABExtractor: cached: ABExtractorProperties(path='/Applications/MusicBrainz Picard 2.app/Contents/MacOS/streaming_extractor_music', version='v2.1_beta2-dirty', sha='5ef873c6c0bf9e39487d8b38e1626a0856df202c', mtime_ns=1642058>
D: 17:53:18,776 webservice/ratecontrol.get_delay_to_next_request:121: ('acousticbrainz.org', 443): Last request was 992 ms ago, waiting 8 ms before starting another one
D: 17:53:18,785 webservice/ratecontrol.get_delay_to_next_request:118: ('acousticbrainz.org', 443): Last request was 1001 ms ago, starting another one
D: 17:53:18,785 webservice/ratecontrol.increment_requests:138: ('acousticbrainz.org', 443): Incrementing requests to: 1
D: 17:53:19,233 webservice/ratecontrol.decrement_requests:146: ('acousticbrainz.org', 443): Decrementing requests to: 0
D: 17:53:19,234 webservice/_init_._handle_reply:540: Received reply for https://acousticbrainz.org:443/191d9967-794e-4d06-b30d-1dcd2fa27b67/low-level: HTTP 200 (OK)
D: 17:53:19,234 webservice/_init_._handle_reply:553: Response received: {'message': 'ok'}
D: 17:53:19,235 acousticbrainz/_init.submit_features_callback:286: AcousticBrainz features were successfully submitted: /Volumes/out5/2022_03_14/SynthwaveVaporwave/Zimmermann, Peter/Z I M M E R M A N I A (Vol. I)/Peter Zimmermann - Z I M M E R M A N I A (Vol. I) - 03>
D: 17:53:19,235 file.update:707: Updating file <FLACFile 'Peter Zimmermann - Z I M M E R M A N I A (Vol. I) - 03 Königspudel.flac'>
D: 17:53:19,237 webservice/ratecontrol._out_of_backoff:222: ('acousticbrainz.org', 443): oobackoff; delay: 1000ms -> 1000ms; slow start; window size 328.000 -> 329.000
D: 17:53:19,306 webservice/ratecontrol.get_delay_to_next_request:121: ('acousticbrainz.org', 443): Last request was 520 ms ago, waiting 480 ms before starting another one
D: 17:53:19,451 acousticbrainz/_init_.get:94: ABExtractor: cached: ABExtractorProperties(path='/Applications/MusicBrainz Picard 2.app/Contents/MacOS/streaming_extractor_music', version='v2.1_beta2-dirty', sha='5ef873c6c0bf9e39487d8b38e1626a0856df202c', mtime_ns=1642058>
D: 17:53:19,800 webservice/ratecontrol.get_delay_to_next_request:118: ('acousticbrainz.org', 443): Last request was 1015 ms ago, starting another one
D: 17:53:19,800 webservice/ratecontrol.increment_requests:138: ('acousticbrainz.org', 443): Incrementing requests to: 1
D: 17:53:19,980 webservice/ratecontrol.decrement_requests:146: ('acousticbrainz.org', 443): Decrementing requests to: 0
D: 17:53:19,981 webservice/_init_._handle_reply:540: Received reply for https://acousticbrainz.org:443/98c455a3-d205-4b4f-9882-279b81dfa700/low-level: HTTP 200 (OK)
D: 17:53:19,981 webservice/_init_._handle_reply:553: Response received: {'message': 'ok'}
Traceback (most recent call last):
  File "webservice/_init_.py", line 572, in _process_reply
  File "webservice/_init_.py", line 559, in _handle_reply
  File "acousticbrainz/_init_.py", line 284, in submit_features_callback
TypeError: remove: path should be string, bytes or os.PathLike, not NoneType
Abort trap: 6

I have an OS Crash stack trace thing too. (The stuff that gets submitted to Apple.)

Here are the exact filenames, because this looks like it might be related...

$ ls -l '/Volumes/out5/2022_03_14/SynthwaveVaporwave/Zimmermann, Peter/Z I M M E R M A N I A (Vol. I)_' | hexdump -C
00000000  74 6f 74 61 6c 20 37 39  32 34 34 32 0a 2d 72 77  |total 792442.-rw|
00000010  78 72 77 78 72 77 78 20  20 31 20 70 68 6f 74 6f  |xrwxrwx  1 photo|
00000020  20 20 73 74 61 66 66 20  20 33 37 30 38 32 35 38  |  staff  3708258|
00000030  36 20 4d 61 72 20 33 30  20 32 33 3a 35 39 20 50  |6 Mar 30 23:59 P|
00000040  65 74 65 72 20 5a 69 6d  6d 65 72 6d 61 6e 6e 20  |eter Zimmermann |
00000050  2d 20 5a 20 49 20 4d 20  4d 20 45 20 52 20 4d 20  |- Z I M M E R M |
00000060  41 20 4e 20 49 20 41 20  28 56 6f 6c 2e 20 49 29  |A N I A (Vol. I)|
00000070  20 2d 20 30 31 20 55 68  20 42 6f 79 21 20 28 52  | - 01 Uh Boy! (R|
00000080  65 2d 57 4f 52 4b 29 2e  66 6c 61 63 0a 2d 72 77  |e-WORK).flac.-rw|
00000090  78 72 77 78 72 77 78 20  20 31 20 70 68 6f 74 6f  |xrwxrwx  1 photo|
000000a0  20 20 73 74 61 66 66 20  20 36 31 39 36 35 35 33  |  staff  6196553|
000000b0  38 20 4d 61 72 20 33 30  20 32 33 3a 35 39 20 50  |8 Mar 30 23:59 P|
000000c0  65 74 65 72 20 5a 69 6d  6d 65 72 6d 61 6e 6e 20  |eter Zimmermann |
000000d0  2d 20 5a 20 49 20 4d 20  4d 20 45 20 52 20 4d 20  |- Z I M M E R M |
000000e0  41 20 4e 20 49 20 41 20  28 56 6f 6c 2e 20 49 29  |A N I A (Vol. I)|
000000f0  20 2d 20 30 32 20 4c 75  76 20 4c 69 6b 65 20 46  | - 02 Luv Like F|
00000100  69 72 65 20 28 4c 75 76  20 69 6e 20 31 39 37 39  |ire (Luv in 1979|
00000110  20 56 65 72 73 69 6f 6e  29 2e 66 6c 61 63 0a 2d  | Version).flac.-|
00000120  72 77 78 72 77 78 72 77  78 20 20 31 20 70 68 6f  |rwxrwxrwx  1 pho|
00000130  74 6f 20 20 73 74 61 66  66 20 20 38 30 31 30 30  |to  staff  80100|
00000140  37 31 30 20 4d 61 72 20  33 30 20 32 33 3a 35 39  |710 Mar 30 23:59|
00000150  20 50 65 74 65 72 20 5a  69 6d 6d 65 72 6d 61 6e  | Peter Zimmerman|
00000160  6e 20 2d 20 5a 20 49 20  4d 20 4d 20 45 20 52 20  |n - Z I M M E R |
00000170  4d 20 41 20 4e 20 49 20  41 20 28 56 6f 6c 2e 20  |M A N I A (Vol. |
00000180  49 29 20 2d 20 30 33 20  4b c3 b6 6e 69 67 73 70  |I) - 03 K..nigsp|
00000190  75 64 65 6c 2e 66 6c 61  63 0a 2d 72 77 78 72 77  |udel.flac.-rwxrw|
000001a0  78 72 77 78 20 20 31 20  70 68 6f 74 6f 20 20 73  |xrwx  1 photo  s|
000001b0  74 61 66 66 20 20 37 36  30 39 30 32 36 38 20 4d  |taff  76090268 M|
000001c0  61 72 20 33 31 20 30 30  3a 30 30 20 50 65 74 65  |ar 31 00:00 Pete|
000001d0  72 20 5a 69 6d 6d 65 72  6d 61 6e 6e 20 2d 20 5a  |r Zimmermann - Z|
000001e0  20 49 20 4d 20 4d 20 45  20 52 20 4d 20 41 20 4e  | I M M E R M A N|
000001f0  20 49 20 41 20 28 56 6f  6c 2e 20 49 29 20 2d 20  | I A (Vol. I) - |
00000200  30 34 20 49 74 27 73 20  46 72 65 73 68 2c 20 49  |04 It's Fresh, I|
00000210  74 27 73 20 43 6f 6f 6c  2c 20 49 74 27 73 20 54  |t's Cool, It's T|
00000220  72 75 65 2e 66 6c 61 63  0a 2d 72 77 78 72 77 78  |rue.flac.-rwxrwx|
00000230  72 77 78 20 20 31 20 70  68 6f 74 6f 20 20 73 74  |rwx  1 photo  st|
00000240  61 66 66 20 20 34 31 30  30 37 37 39 34 20 4d 61  |aff  41007794 Ma|
00000250  72 20 33 31 20 30 30 3a  30 30 20 50 65 74 65 72  |r 31 00:00 Peter|
00000260  20 5a 69 6d 6d 65 72 6d  61 6e 6e 20 2d 20 5a 20  | Zimmermann - Z |
00000270  49 20 4d 20 4d 20 45 20  52 20 4d 20 41 20 4e 20  |I M M E R M A N |
00000280  49 20 41 20 28 56 6f 6c  2e 20 49 29 20 2d 20 30  |I A (Vol. I) - 0|
00000290  35 20 4f 66 66 20 54 68  65 20 45 64 67 65 2e 66  |5 Off The Edge.f|
000002a0  6c 61 63 0a 2d 72 77 78  72 77 78 72 77 78 20 20  |lac.-rwxrwxrwx  |
000002b0  31 20 70 68 6f 74 6f 20  20 73 74 61 66 66 20 20  |1 photo  staff  |
000002c0  34 33 34 31 35 30 31 32  20 4d 61 72 20 33 31 20  |43415012 Mar 31 |
000002d0  30 30 3a 30 30 20 50 65  74 65 72 20 5a 69 6d 6d  |00:00 Peter Zimm|
000002e0  65 72 6d 61 6e 6e 20 2d  20 5a 20 49 20 4d 20 4d  |ermann - Z I M M|
000002f0  20 45 20 52 20 4d 20 41  20 4e 20 49 20 41 20 28  | E R M A N I A (|
00000300  56 6f 6c 2e 20 49 29 20  2d 20 30 36 20 54 68 65  |Vol. I) - 06 The|
00000310  20 4c 65 67 65 6e 64 20  6f 66 20 42 69 6c 6c 79  | Legend of Billy|
00000320  20 4a 65 61 6e 20 28 50  61 72 74 20 49 29 2e 66  | Jean (Part I).f|
00000330  6c 61 63 0a 2d 72 77 78  72 77 78 72 77 78 20 20  |lac.-rwxrwxrwx  |
00000340  31 20 70 68 6f 74 6f 20  20 73 74 61 66 66 20 20  |1 photo  staff  |
00000350  32 34 39 30 33 39 32 32  20 4d 61 72 20 33 31 20  |24903922 Mar 31 |
00000360  30 30 3a 30 30 20 50 65  74 65 72 20 5a 69 6d 6d  |00:00 Peter Zimm|
00000370  65 72 6d 61 6e 6e 20 2d  20 5a 20 49 20 4d 20 4d  |ermann - Z I M M|
00000380  20 45 20 52 20 4d 20 41  20 4e 20 49 20 41 20 28  | E R M A N I A (|
00000390  56 6f 6c 2e 20 49 29 20  2d 20 30 37 20 49 6e 74  |Vol. I) - 07 Int|
000003a0  65 72 6d 65 7a 7a 6f 20  38 35 27 2e 66 6c 61 63  |ermezzo 85'.flac|
000003b0  0a 2d 72 77 78 72 77 78  72 77 78 20 20 31 20 70  |.-rwxrwxrwx  1 p|
000003c0  68 6f 74 6f 20 20 73 74  61 66 66 20 20 33 37 35  |hoto  staff  375|
000003d0  30 31 38 34 33 20 4d 61  72 20 33 31 20 30 30 3a  |01843 Mar 31 00:|
000003e0  30 30 20 50 65 74 65 72  20 5a 69 6d 6d 65 72 6d  |00 Peter Zimmerm|
000003f0  61 6e 6e 20 2d 20 5a 20  49 20 4d 20 4d 20 45 20  |ann - Z I M M E |
00000400  52 20 4d 20 41 20 4e 20  49 20 41 20 28 56 6f 6c  |R M A N I A (Vol|
00000410  2e 20 49 29 20 2d 20 30  38 20 45 6c 65 63 74 72  |. I) - 08 Electr|
00000420  69 63 20 48 65 61 72 74  20 28 66 65 61 74 2e 20  |ic Heart (feat. |
00000430  44 61 72 69 61 20 44 61  6e 61 74 65 6c 6c 69 29  |Daria Danatelli)|
00000440  2e 66 6c 61 63 0a 2d 72  77 78 72 77 78 72 77 78  |.flac.-rwxrwxrwx|
00000450  20 20 31 20 70 68 6f 74  6f 20 20 73 74 61 66 66  |  1 photo  staff|
00000460  20 20 20 33 36 36 31 30  36 39 20 4d 61 72 20 31  |   3661069 Mar 1|
00000470  34 20 31 33 3a 30 31 20  63 6f 76 65 72 2e 6a 70  |4 13:01 cover.jp|
00000480  67 0a                                             |g.|
00000482

FLAC files themselves are not corrupt:

$ flac -t  /Volumes/out5/2022_03_14/SynthwaveVaporwave/Zimmermann\,\ Peter/Z\ I\ M\ M\ E\ R\ M\ A\ N\ I\ A\ (Vol.\ I)_/*flac

flac 1.3.2
Copyright (C) 2000-2009  Josh Coalson, 2011-2016  Xiph.Org Foundation
flac comes with ABSOLUTELY NO WARRANTY.  This is free software, and you are
welcome to redistribute it under certain conditions.  Type `flac' for details.

Peter Zimmermann - Z I M M E R M A N I A (Vol. I) - 01 Uh Boy! (Re-WORK).flac: ok
Peter Zimmermann - Z I M M E R M A N I A (Vol. I) - 02 Luv Like Fire (Luv in 1979 Version).flac: ok
Peter Zimmermann - Z I M M E R M A N I A (Vol. I) - 03 Königspudel.flac: ok
Peter Zimmermann - Z I M M E R M A N I A (Vol. I) - 04 It's Fresh, It's Cool, It's True.flac: ok
Peter Zimmermann - Z I M M E R M A N I A (Vol. I) - 05 Off The Edge.flac: ok
Peter Zimmermann - Z I M M E R M A N I A (Vol. I) - 06 The Legend of Billy Jean (Part I).flac: ok
Peter Zimmermann - Z I M M E R M A N I A (Vol. I) - 07 Intermezzo 85'.flac: ok
Peter Zimmermann - Z I M M E R M A N I A (Vol. I) - 08 Electric Heart (feat. Daria Danatelli).flac: ok

I just tried to reproduce this a third time, with only these eight files, and it did not crash, and seems to be working ok...

The first and second times this happened, I had several dozen albums loaded in Picard, and I was running "Submit Acoustic features" over all of them... and all of the albums except the above album, and one other one, got the green status checkmarks... Hitting "Submit Acoustic features" the second time on the above album is what crashed Picard halfway through.