That's right, if you have a channel window open, and it is being logged, then while connected the channel.N.log is in the Network folder. The moment you disconnect, that channel no longer has an associated network, so the channel.N.log in the Network folder is closed,
Part of the user's confusion could be that it appears that the channel does have an associated network to some degree. If you join Network1 and Network2, and create or join #test at both, then type in the channel windows
//echo -a *** $network $active
shows the same thing before and after we disconnect from both networks without closing the channel windows. We just don't have a $server value after disconnecting.