I'm sure you've heard of this one MANY times.  The 2nd player in any world, cannot get in.  The second screen gets stuck on "Building Terrain".  Tried reboot, uninstalling the game, factory reset of the game, disconnected power for 10 mins, etc.  Support told me, "hotfix coming very soon".  Considering I am seeing this issue being reported as far back as 2017, that sounds unlikely.

Playing on XBOX Series X.