They probably compute the ID from the registry on server join then.
In that case the ID changer has to be remade. It isn't too hard, but you need some experience with mod-apping and possibly code caving.
would probably look for the function that generates the code and look to see where the final ID gets set into memory, copy that function, go to the beginning of the generate ID function, jump to your new section in memory where you store your fake ID, jump back to somewhere in the stack the ID isn't altered before that function ends and force it to your new ID.
so basically something like if this was the original code
this_is_the_generator_function_bullshit()[
grab_shit_from_registry
do_magic_shit_to form_ID
send_id_to_memory
]
you want it to look more like
this_is_the_generator_function_bullshit()[
grab_shit_from_registry
jump_to_my_new_function
jump_to_old_place_in_memory
send_id_to_memory
]
Now, this is just shit i pulled out of my arse (sym special) as i dun fk with the game, but its so over simplified and general that it cant not work.