WordPress developer needed to resolve some issues

Description

I am having trouble with the media library on my WordPress website.
Sometimes I receive an error when trying to delete an image from the library. Also, in certain categories - new featured thumbnails are showing as "unattached," even though they are showing up in the post fine.
I believe something went wrong when I was cleaning up the SQL database months ago. I didn't notice the issue until quite a bit after the fact, making a backup restoration nearly impossible.