Hey Alexis – realise your post here is pretty old, but I think I have encountered exactly the same problem, Responsive Design Time not working in Premiere on some Mogrts (built in AE) as it should. Premiere is ignoring the ability to time-stretch the clip, even though the Intro and Outro regions usng RDT are applied in the AE comp.
No audio in the Mogrts, or time remapping..but they do have a few expressions in there, but I can’t see how these would affect it.
Just wandered if you ever found an answer, or if it’s a bug – I’m stumped!
?