control, shift not selecting all songs

[fergiej97]

Premium user here on windows 10. I have 3,700 songs and I want to put them into one folder but when I control shift and click it doesn't select all my songs. It will select certain amounts in small chunks and miss a few or even hundreds in between.

I can only seem to select 800 - 1,200 songs at a time. Also, it's not always the same songs. seems rather random. I tried uninstalling and reinstalling but nothing has changed.

the pic below shows roughly what happens