I encountered an issue like 2 years ago and got it solved just today.
When using the "Local Files" function, Spotify won't show the names of certain songs. It will play them normal though. Several users already tried deleting the "Storage cache" or reinstalled Spotify but that didn't helped.
Screenshot (from closed topic):
Delete local file cache. To do this, first close Spotify completely, then go to %appdata% > roaming > Spotify > User > Your Account Name and delete the file "Local-Files".
I hope this helps some of you who got this issue too. I wish I would've known this like 2 years ago where I stopped using the local files function completely because of this annoying issue.
What I’ve found is that if I have any issues with local files or I do any metadata changes to them then the best thing to do is to disable local files in Spotify app and then delete the local files related setting files in appdata or application support and then re-enable local files.