I have a player who I had in another group last week that can’t join another group I’ve invited them to. I removed them from the first, but still no go.
It sounds like it might be account related so I’d like to have the player who can’t join your group reach out directly to our support team. They’ll be best able to work through this and figure out what’s going on.
My wife experienced similar with her account. She kept trying to sign in with her email and a password, but it wouldn’t work. She then tried signing in with google and it worked fine.