Hi Ian... Exactly! I did a quick search and missed your excellent posts! Please Team Vegas -- this is a standard feature that should have been added years ago. There are tens of thousands of users that would use this feature immediately.

Yes, keyframe interpolation is the most frequent feature request I've ever seen. And the developers are definitely heeding the request, but right now there are not enough engineers, so please give them enough time. The best we can do is explain how revolutionary this feature will bring for Vegas.

In my opinion, adding more keyframe interpolations for Mask, 3D Parent/Child Track Motion and Transition Progress Envelop will make Vegas Pro become a game-changer.

@sam-s7089, in the meantime, just to make sure you know, you can right-click the keyframe and choose Fast and/or Slow to accomplish at least some level of simple easing.

In your screenshot, you would set the first keyframe to fast which would cause it to ease into the second keyframe and you would choose Slow on the second keyframe to ease out of it.

Yes, I am well aware of all of the other shapes being discussed in other threads for future development wishes. I'm just making sure you don't miss the options that are already there.