where did you rip the audio files on your B2 and what format are they in, MP3, Flac, WAV ?
When you rip on a B2 it initially rips to WAV and stores album art in folder.jpg file in the album folder on disc,
If you are compressing, I.e Flac or mp3, the B2 will automatically compress this when it is “idle” if you have chosen to store your audio in a compressed format.
You can force immediate compression by the “compress now” menu command.
It is only when the audio file is compressed that the album art metadata tag is populated using the contents of the jpg file.