Selecting the default character/skeletal mesh (or any skeletal mesh) in the viewport, right-clicking and transforming it so it mirrors on the X,Y, or Z axis will cause the physics to act erratically when applied.
If the skeletal mesh is not mirrored, physics act as expected.
*See attached image to expedite repro steps
1. Open Third Person Project in UE4.10
2. Select the player character in the viewport
3. Right click and select Transform/Mirror X or Mirror Y
4. In the Details Panel, select "Simulate Physics"
5. Play in Editor
RESULTS: Skeletal Mesh will spin/move erratically
EXPECTED: Skeletal Mesh to collapse like a rag doll as it does when not mirrored
Head over to the existing Questions & Answers thread and let us know what's up.
| 11 | 
| Component | UE - Simulation - Physics | 
|---|---|
| Affects Versions | 4.10 | 
| Target Fix | 4.21 | 
| Created | Dec 1, 2015 | 
|---|---|
| Resolved | Aug 8, 2018 | 
| Updated | Sep 27, 2018 |