That makes sense and is something that was suspected with one-way pricing. Of course, it would be nice to have an announcement of some sort if that is what is happening here.
What does UA do in this situation? Do they allow stopovers?
Yes, UA does allow some -- for no additional mileage price -- on roundtrip awards. They allowed that even after they shifted to one-way pricing of award travel.
AA allowed free stopovers at North American international gateway cities (on one-way or roundtrips, in one or both directions) until earlier this year.