I post it as a suggestion because I’m sure the bug is well known.
Sometimes the 1st person camera goes inside the character and consequently the wielded object, weapon or tool, cannot be used up and down, and the head of the avatar also doesn’t move up and down any more.
Maybe a “CameraReset” console command (user mode, not admin) which would reset this camera could make “everything” work again and temporarily help players to avoid disconnect/reconnect or reload the game (single player) until the bug is found and solved.
regards.