To anyone who may be able to help,
SS5 (featured heavily on Robin's YouTube videos as 8BitShowAndTell) is busted on MiSTer, and I've thus far been unsuccessful in drumming up interest in fixing it.
See this bug report on Github:
https://github.com/MiSTer-devel/C64_MiSTer/issues/156
I'm hoping the issue (and fix) is a simple one, but at this point I'd just like to be able to convince someone to at least look at it. SS5 is so iconic it'd be a shame if it were never to be fixed, and it sure would be nice to follow along with Robin on MiSTer.
Any takers? =)