Thanks for that… I’d tried that one as well.
I actually just found the answer, strange that I’ve never come across this in 10+ years of AE use…
I had three looping movie clips and I was animating them across the screen. To create an illusion of randomness (they were all rotating the same direction in their loop) I reversed the rotation of one with a -100% time-stretch. That one was the first clip I was trying to animate.
I gave up for the moment on seeing keyframes on that one and moved on to the next of the looping movie layers and lo and behold, I see keyframes! I go on a hunch and precompose the -100% time-stretched clip. I animate the pre-comped clip and yup, there is a visible motion path and keyframes.
So, I suppose experienced AE users probably knew this, but for some reason you can’t see motion paths or keyframes on time-stretched clips? I gotta say that’s kind of lame.