AE 24 rotobrush/scoping updates still come with significant issues

I have been having a hell of time with AE's rotobrush/scoping feature, but was hopeful that the latest AE (24) version would fix the rotobrush issues, as advertised. Whereas before, this feature would prompt a doom loop of endless frame propogation, now AE 24's rotobrush tool simply won't event capture the object I identify using the green marker. It seems to capture the whole frame only. This is after I've cut up my clip in 20 sec. segments, rendered these pieces out in PP, and opened them individually in AE (this was suggested as a method for avoiding the frame propogation doom loop). All of this is extremely discouraging and I don't know how a feature like this can be released when there are clearly longstandinging, persistant issues with it.