There are issues with the way Physics is being handled with physical materials. Having a physical material setup with a restitution of 1 and a high max depenetration value will result in no bounce.
Portions of email thread regarding this subject:
"Tried some simple test. If you take a ball with restitution 1 and very high max penetration velocity it will not bounce off a wall with no gravity.
I verified that the physical material is correct on our end. Talking to NVIDIA this sounds like a bug and waiting for info from them."
A video demonstrating what Ori pointed out. The White mesh is the Physical Material. The Blue is a default colored material with no Physical Material applied. First step shows projectile speed set to 206 and second part is set to 205 that stops the mesh from moving.
These are the steps I used based on what Ori mentioned above from the description. Not entirely sure this is accurate, but I do see a result. (Check the attached video)
1. Open UE4
2. Create a Physical Material with a restitution of 1
3. Create a material and apply the physical material to it
4. Set up a wall and apply the material to it
5. Setup a projectile movement BP to push your sphere mesh
6. Set the projectile speed to 205
7. Place this in the level facing the wall
8. Set the sphere max depenetration value to a high value.
9. PIE and you will see the mesh stop when it hits the wall
10. Change the velocity to 206
9 PIE and you will see the mesh bounce back.
Head over to the existing AnswerHub thread and let us know what's up.