I have (or had) 31,000+ tracks on my B2, taking up about 380GB. I ripped some CDs this morning with about 100 tracks total, and started to compress about an hour ago. I noticed that it was stuck on 0% at the outset, but figured it would start working soon.
When I checked on the progress, only READY was displayed, with the red light flashing. I tried pressing PLAY/SAVE to get to the SAVING screen, but nothing happened, so I turned the B2 off and let it rest a bit.
Upon turning it back on, here's what it says I have:

Missing juuuuust a few tracks, eh? Also gone is the playlist I've been building. But the Used space is correct, so something's in there. Incidentally, the 10 albums it shows are actually just 4 .flac tracks, listed several times:

Thanks for your help.