Has anyone else seen the following with the OSD popup textbox?

I have one setup, with a nonvisible/hidden button to receive callerID from Greg's axc interface to Asterisk. Works fine.
However, I see the OSD also pops up blank for other messages which are targetted at the device even if there is no button to filter it. This happens because I regularly generate a number of status xAPOSD/message.display messages targetted : *.*.<roomname> and the joggler is UKUSA.xAPFlash.<roomname>