I'm having trouble using Picard with a large number (5000+) of files. Sometimes, the track selection will get "stuck" and fail to update when I choose a different track on the right hand pane. Regardless of what I click on, the info/edit box at the bottom will remain fixed on the wrong file.
When this happens I can save, edit, etc. this one track but no others.
If I "remove" the track or album, then I get one click to select a new file ... after this, the new chosen item gets "stuck" again!
The only resolution I have found is to quit and restart. Frustrating, I can't even highlight my current work and save it, so I have to restart from scratch. I could work around this by working with smaller batches, but it's definitely annoying.