Issues with nested clips, trimming, and reverse speed.
While nesting a source clip in order to both stabilize it inside the nest and then apply reverse speed on the nest, I discovered a glitch with trimming and expanding the nest on a timeline.
After creating a nest, I went inside the nest itself to trim the source clip to my desired In point and Out point because I did not want to waste rendering time stabilizing parts of the clip that I wasn't going to use.
Once the stabilization was complete I applied reverse speed on the nest on a timeline. But I discovered that the nest would suddenly become black video toward the end of the nest. It turned out that it would become black video at exactly the amount of frames that I had originally trimmed off the beginning of the clip inside the nest. But Premiere was treating this as if the nest hadn't had reverse speed applied. I soon discovered that the amount of frames trimmed off the beginning of the clip was being removed from the beginning of the reversed nest rather than the ending, and vice versa. If I trimmed the nest back past where the video would become black it would then not allow me to expand the nest to the full size of the clip again, probably because it was still seeing the source lip's media as not reversed and thus thinking it had ran out of media on that end of the clip.
Essentially the nest is not seeing the clip parameters and trims as reversed even though the nest itself is reversed. I ended up just stabilizing everything and then setting the same in and out points, but this was a waste of rendering time and unintuitive.