All Frames Are Not Fully Deleted From Animation Sequence When Attempting to Create an Aim Offset

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. 

Repro Steps:

1. Create a TPS blank project.
2. Migrate/Add the Animation Starter Pack to the project.
3. Open the Aim_Space_Hip Animation Sequence, right click, and delete all of the keyframes. 

Expected: All keyframes are deleted.
Actual: One keyframe are a percentage of it remains, despite multiple attempts to delete it.