I tried to reproduce it, but haven't noticed anything unusual. Maybe there's something more to it than just having empty tags?

Just now. It was a very busy week for me, so the changelog doesn't look spectacular:

• Fixed crashes on mime_open (opening files from a file browser should work now).
• Fixed some untranslatable strings.
• Updated translations: Spanish (thanks to Zentenario), French (thanks to mirandir).
• New translation: Romanian by ioncelmare.
• Restoring default album art supports embedded images.

If you want to test the first thing from the changelog, edit "/usr/share/dbus-1/services/com.nokia.mediaplayer.service" as root, so the line:
becomes:
This will replace the stock player until you edit the file back.

Regarding translations, I've noticed that "%n clip(s) added to now playing" is often misinterpreted as "%n video(s) added to now playing". In reality, "clips" in that phrase are "audio clips", so I've got a request for translators to check for that mistake and send me corrections (that's just about 2 lines, so preferably PM me them or paste into this thread.

Also keep an eye out for phrases that are too wide to fit their space, it's possible to split them into two lines in most cases. This solution sometimes can cause a few pixels of the text to be invisible, but I'll be looking for a way to make the font smaller (the only solutions I came up with would be a mess or require reimplementing some low-level Qt stuff, so I don't know when it's going to be fixed).

Not in OMP itself, but it uses Tracker's database, so you can configure WatchDirectoryRoots and NoWatchDirectory options in "/home/user/.config/tracker/tracker.cfg" to include or blacklist directories.