Music desktop app library keeps rolling back / not staying updated / cloud sync issue

Is anybody else having this issue lately and if so, has anybody managed to find a fix? I've installed all the latest updates in the hope is was a bug but it doesn't seem to have sorted anything at all. It's been happening - as far as I have noticed, as I haven't been using it a terrible lot these last few months - for a month or so, maybe longer.

I'm finding that, for example, if I create a playlist and add, let's say, 20 songs to it, but then come back later and add 15 more... If I come back a day or two later, the 15 tracks I added later aren't there anymore.

I'm finding that if I delete 100 tracks from the library, the next day, they're back, and I don't want them. And it doesn't matter how often I delete them.

I'm finding that if I name a dozen playlists, their titles have all disappeared a day or two later (as well as a lot of the content I added to them) and reverted back to a previous title or "Untitled 9" or something.

Basically, many changes I make to my library just aren't sticking and it's becoming unbearable. Any tips?