Two interesting things:
1. I just got an out-of-memory panic:
*PANIC*
audio_reset_buffer(): OOM!
Right before this happened, I had plugged it into USB, rsynced tracks and playlists to it, ejected it and finally asked Rockbox to initialize the database. (After the panic, I restarted it, and it displayed the message "Committing database [1/10]" and then continued to start up.
2. My playlists are only showing the track title, no artist. The playlists I copied have EXTINF data, so Rockbox seems to be ignoring that. Is this normal? All I can find on the subject is this:
https://www.rockbox.org/tracker/task/7652