Might want to contact ASrock explaining what you've found. I don't think this is right. There's no warning on the product page at Amazon mentioning it wont work with Pinnacle in it's current state. Something has changed.
Was the seller Amazon or a partner on Amazon?
Amazon, not a partner. The system DOES boot (or did, already took it apart), loaded Windows 10, got to desktop, decided to see if there were any bios updates that I'd be interested in on the support page and saw the recommendation (or non-recommendation). The support page doesn't say earlier generations won't work, they're just NOT recommended
. So then, uncertainty crept in, e.g., what if the system becomes unstable during gaming, or other situations? I'm busy during the holidays so I don't have time to do a proper stress test/ burn in/ bench mark on a new build like I usually do, and I don't want to wait too long that I can't return the board.
It's not just this model of board either, the ASRock B450M-HDV R4.0 has the same warning, as does the B450M Steel Legend, probably others. It's an ASRock thing apparently, I don' see any such warnings on the support pages of the other popular brand motherboards for sale on Amazon or Newegg. Still a head-scratcher.