It seems in some situations Picard will not show the barcode in the "other versions" context menu even though it's returned by the API.
In other cases it will show them as expected
In yet another case it literally shows "[no barcode]" even though the "no barcode" flag has not been set on the release while for other releases where the barcode is blank it will show nothing

Tested releases:

• https://musicbrainz.org/release/7dcfd1f2-20b9-4d34-bab2-e74eec5b45a5
• https://musicbrainz.org/release/06a6b573-4112-4b08-99c7-a9a6704777b8
• https://musicbrainz.org/release/c011fa93-2eed-4a54-9b6a-6609c48e38d4
• https://musicbrainz.org/release/de4a081c-8348-4c33-beef-1869f6441abd

This was tested on Windows with portable build and default settings