It's been reported that using the rolling ball physics on a flat landscape will cause the rolling ball to bounce when it crosses a seam. It does not happen on every single seam, but it happens pretty frequently. Must be on low FPS though.
Possibly related to: [Link Removed]
Also tested in 4.8 Main: UE4/Promoted-CL-2513846
1. Create a new rolling template
2. Delete the floor
3. Replace the floor with a flat landscape
4. Press Play
5. Enter the console command: t.maxfps 10
Head over to the existing Questions & Answers thread and let us know what's up.