I suspect what you are seeing is something different. There can be buckets available for sale on a flight but no active fare for that class for the destinations involved. The buckets may be there for other routings. The R and RN should not have this property with the possible exception of a direct flights with multiple legs where the waitlisted upgrade is for the single end-to-end (and I'm not sure this would be how the waitlisted segments would actually appear). R should clear on a leg by leg basis if R>0 for the leg. What folks are seeing (myself this morning) seem to be computer system failures where the waitlist simply isn't being processed even though someone initiating a completely new request will clear instantly.