Game thinks you're in a full party

This occurs after I attempt to join a friend's party, but that party is full. I get a message saying I could not join the full party.

After this occurs, I cannot click the empty diamonds on my lobby screen to invite others and cannot click player's banners to invite them after a game has ended. In effect, it seems like Apex is mistakenly treating me as if I was in a full party in terms of seeing my friends list, inviting squad mates, etc.