weird issue with invisible player

on my test server with 3 players there is one player who regularly cant see anyone properly. we can all see him fine, but he can only see our player models standing still in seemingly random spots. its like this for the whole time he is playing on my server, its not a degenerative thing where he can see us properly for a while then it breaks. anyone heard of this before? we are all using up to date clients and the server has been running 953 and up (i have tried a few dev builds and im currently using 982).

thanks for any help.