This may seem a bit odd and probably carried over from the PS4 problem, but are you the host? If so, I not sure what could be wrong.
Otherwise when playing a co-op game with just one friend, for whatever reason when they are not the host, if they click their own head, they'll warp to the host. I have no idea how much this complicates things when there more than two playing. This is least how me and friend (who was not the host) got it working.
Note: you do not need to be on teams to make it work, but it might help.