I know this Thread is very old, but I arrived here just today. Because I was well aware of the keyframe stretch feature, and use it now and then. But this morning I could not get it to work! frustrating to say the least.
Even tried closing AE, and re-launching in case my keyboard was glitching. Anyway I noticed some specific behavior about the feature. It seems like you HAVE to grab the full span of keyframes, no matter how many layers you highlight at once. In other words the very beginning keyframe, and the very end.
You can see in my screen-grab. Originally I was trying to Alt+Drag on the outer-most keyframe on Layer (Color-4). Which at a quick glance glance seemed like the furthest keyframe. But the feature would not work AT ALL. Wasn’t until I grabbed the true outer-most keyframe on layer (Color-6), then alt+dragged and the feature worked again. : )
Was interesting to me, so hopefully it helps someone else out.
