archive folder in apple mail after macos catalina upgrade

Since I upgraded to Catalina, I find a folder called Archive keeps appearing in the mail app on my Macbook Pro. New emails will go to Archive instead of to my Inbox, then the Archive folder disappears again and the emails go with it, even after I've moved them to the Inbox. Also a folder called Gmail appears and then disappears and there's a number one on the Important folder even though there are no unread messages currently. All the emails are present and perfectly normal if I go to my Gmail account in a browser but I don't want to be forced to use Gmail online because Mail has started randomly deleting emails. I contacted help this morning and fixed the problem by deleting my Gmail account from Mail and then adding it again, but it's happened again already and I don't want to have to keep doing that. Does anyone know what's going on and/or how to fix it?