Triggerbox volume incorrectly forces physics objects to act at rest

If a phsyics actor set to start awake is placed at the top of a trigger box, it will remain at rest.

Regression? (No), issue (does) occur on 4.10.4

1. Open editor (any project)
2. Add a cube mesh to level
3. Set to movable>physics enabled>start awake
4. Add a trigger box to level
5. Press simulate
6. Select cube
7. Using the transform widget, place the cube at the very top of the trigger box as shown in the attached image

Results:

Cube remains stationary

Expected cube falls once LMB is released.