Dogo, some findings about this bug.
I recently bought a vinyl for "Martin L. Gore - Counterfeit e.p." and I had access to these WAV files.
https://www.discogs.com/release/2148841 ... terfeit-EP
I compressed to FLAC 1.4.3 and embedded a 50kB album art.
To my surprise, VLC read these FLACs differently than the "standard CD" FLACs...
The first time, really, the first time it read, it didn't read the tag, but I think it got the intentional correct way to display the artwork like I was saying.
Take a look here:
https://pasteboard.co/S8koLzfnOzG6.jpg
Then, if gone back, and pressed the file again, it will read the tag, but the cover art is gone.
https://pasteboard.co/Blp6QDQeThPg.jpg
Another strange thing is that, after this process, the FILES will show up the album art in the file thumbnail.
https://pasteboard.co/zy0TmZu5xkMu.jpg
So, these FLAC files are 24/192, different from the CD material 16/44.1.
Perhaps this has something to do with this...
I hope these findings help you with tracking where the issue exactly is.
If you want me to do more testing, let me know. I don't know what it could be - the FILE specs, the tags, the position of artwork in the tag...
I just know that I can see a light at the end of the tunnel.
Cheers.