Not many helpful people here lol. Yeah it is tricky to get it right, if you haven't worked it out soon i'll dig a bit deeper into the code for you if you like. Masks are always sent at the end (they have to be because you need to end the bit access to send regular bytes). They are usually appended with a separate buffer during the rest of the updating. One thing to check: are you adding your single player to the list? All 255 local players within distance need to be in the list.