I'm having the same issue with about 11k songs, and when I contacted support they said the problem was caused because that number exceeds the 3,333 limit, but I have trouble thinking that's true. Is there really no way to use Spotify to play local files with a large library?
I would assume most of my local files are available through Spotify, but I have no idea how to look into that so that I have a local file folder monitored by Spotify that's under the 3k limit.
It's a weird issue because it's not throwing up an error message to help troubleshoot. It just freezes, or locks up the whole computer. If it is about limits, shouldn't there just be an error message to tell you that?
Update: after posting, with no further efforts on my part, all my local files seem to appear. Haven't tried playing them but at least they're showing up. Bizarre.