Incorrect restitution behavior for physical material set to 1 whereby momentum is gained during the simulation

Setting a restitution of 1 for a ground material and a restitution of 1 for a ball that bounces on the ground should keep the ball bouncing at the same height consecutively. Over the course of time the bounce height will gradually increase rather than staying at the same height.

• Project attached with everything already setup. Just press play.
• Video attached

1. Open UE4 (or attached project to see the final result)
2. Create Two Physical Materials with Restitution of 1
3. Create two Material with each of the physical materials assigned appropriately
4. Place a sphere in the scene above the ground with Simulate Physics checked
5. Apply Material 1 with Physical Material 1 to the ball
6. Apply Material 2 with Physical Material 2 to the Ground
7. *Optional* place a mesh as height reference in the scene
8. PIE/simulate (easiest to view from front or side view)

Results: With the restitution of 1 on the Physical Material for the Ball and the Ground the ball will gradually start to bounce higher the longer the simulation plays.

Expected: Using a restitution of 1 and 1 for the ground and the ball should keep the same bounce height every time rather than gaining height over a given time.

Incorrect restitution behaviour