Occurs 3/3 Times
*Regression *does occur: Tested in //UE4/Release-4.27.2 @ CL18319896 and all frames were able to be deleted from the Aim_Space_Hip Animation sequence.
Expected: All keyframes are deleted.
Actual: One keyframe are a percentage of it remains, despite multiple attempts to delete it.
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-151408 in the post.