Hi Gordon,
Sorry you are having problems with this. If it’s any consolation, most people do because the currently posted KnowledgeBase instruction doesn’t appear to be consistent with the 8th Generation BIOS. Fortunately, there is getting to be enough accumulated knowledge that can help you get this done. Please see what others have done to get past this step:
I’m hoping who ever wrote the original KnowledgeBase article will update for the new NUCs, but I’m just a Roon User like you.