Sorry, I assume people know my acronyms
FTRT = Faster Than Real Time. I guess I could have said offline bounces to be more clear. (I edited the title of the post now to be more clear)
But you can only make one plug-in mono/stereo on a channel, even if the other plug-ins are inactive.
But regardless, yes, I have found a work around, but if other people are able to replicate it, it should be a bug that is addressed. It probably also means that any time people use a mono/stereo plug-in and then a plug-in after that, it will not render properly on an offline bounce.