This cannot be solved because it is because of the very design of that module...
ChanServ (and any other services pseudo-client for that matter) is not meant to be in a channel. Anope is not aware of its existence like it is for botserv bots. So when a module forces one of these clients into a channel, the ircd will know about it, but anope won't. So to anope a channel with only chanserv in it doesn't exist, whereas for the ircd it does.. this causes desyncs which lead to the problem you mentioned, but also breaks cs unban, invite and some other things..
There are other modules you can look into that avoid these problems, but because it requires much more complex code, the majority of the modules that put pseudo-clients in channels do it the bad way. There are 2 modules I know of that shouldn't cause any problems: my
cs_inhabit_registered and Adam's
m_chanserv.
