Outlook error when moving msg

Hello,

I've just installed Office 365 on my brand new Lenovo laptop (Win 10 ver 1909). I have 5 Gmail accounts set up. When I try to file a message in a pre-existing folder I get an error that the message can't be moved because it's been changed (not!). The first time this happened, I went the long way 'round and right clicked and selected move that way. But now it won't even let me do that. I need to resolve this or abandon Outlook, as I have a bazillion emails that need to be organized. Can someone help me?