Foobar2000 is miles ahead of Groove, so kudos for that!

The two issues I'm getting are:
1. When I select 'shuffle all tracks' it only seems to shuffle about 350 tracks (out of 1300+), I think this is because most of my tracks are labeled under 'unknown album'. Shuffle all albums seems to get all tracks.
2. This is an issue in Groove too: A lot of songs that have an 'unknown album' seem to be getting album art incorrectly. I think that's because at least 1 of those 'unknown album' songs doe have actual album art included, which is then getting reused for all the other songs.

I hope I was clear enough and wish you good luck on development