Current LibreElec is version 8.2.5. I tried to revert back to 8.2.0 without any change in playback. Alpha is an option I haven't tried yet.
The FLAC files have all the same setup when it comes to tags (content), but I will take a closer look if I can detect any difference in version of mp3tag that I'm using.When I got the test album working I decoded the FLAC files from 1.2.1 and then encoded them using version 1.3.2,
To encode I use: FLAC - download with GUI: New FLAC Frontend