Reproduction steps:

1. FLAC file with embedded cover art (native PICTURE block, confirmed via metaflac --list)
   METADATA block #3 type: 6 (PICTURE) ← This is a native FLAC picture block ✓ type: 3 (Cover (front)) ← Correctly tagged as front cover ✓ data length: 1596908 ← ~1.5 MB image present ✓

1. Picard settings: "Clear existing tags" ON, "Keep embedded images" ON
2. Cover Art settings:
   "Embed cover images into tags" ON
   "Save cover Images as separate files" ON
   "Overwrite the file if it already exists" ON
   "Always use the primary images types as the file name for non-front images" ON
   "Provide Cover Art" All of (or "Local Files" on but no cover.jpg in the picard import folder)
3. Load file into Picard — embedded image shows in left pane
4. Match to album — right pane shows 0 images for the album but the Embedded Cover art is still shown and possible top open.
5. Save

Expected: Embedded image preserved
Actual: Embedded image deleted

Environment: macOS Mac Mini M4, FLAC files, Picard version [2.13.3]

relevant community post, without solution: https://community.metabrainz.org/t/why-is-picard-removing-embedded-images/760605