Hi, Laura! Not currently a Mac user, but here are some Google results.

HighDef: thx. This seems more random. Or trudging, ie, there's a timeline to choose from amd either labels aren't showing up or I can't select a specific backup.

I come to not depend on Time Machine for long term backups.

beken: no, but I'm looking for something from April. It's not on my long term backup drive or in time machine. It's just gone! 😓

Oh, I'm sorry. That is so frustrating.