Second co op friend’s sign not showing up

Hey guys curious if there’s an item needed for the second person, we’re trying to bring in 2 people in but one of our friend’s sign isn’t showing up. We’ve tried changing to unrestricted, we have passwords set, and I’m even well beyond the level that the person is bringing me in but the 2nd friend is at his level. Curious if you guys have any idea what’s good with this? Not sure what to do.