I did some further research on this, the problem is with mIRC. Not only is mIRC the only programme affected by this (as far as I have sought to find out) but the case change is only seen by the users of mIRC that are in the affected room and also only in the room that the mode change had taken place, which is understandable since it's a room mode we are talking about, none-the-less the problem doesn't occur in the java applet or in Pirch. That said, and like with any problem, the issue has to come down to what is most commonly affected, an IRCd or a client. In this case one client is affected and by an undocumented issue, therefore the client (in this case mIRC) is at fault.