When using a raycast trace against a blueprint that has a child component with multiple materials will cause the editor to crash after a few times. This will not be an instant crash, but requires the trace to hit and leave the mesh a couple of times before the crash will occur.
Using the attached project:
1. Open project
3. Press Space Bar to simulate physics on the asset
4. Move close and drag the raycast over the multi material box a couple of times until it crashes.
1. Open UE4
2. Create a line trace for your player character
3. Create a new Actor BP with a Parent Static Mesh with a single material, and a child static mesh component with at least two materials.
4. Set a key press event to simulate physics for the actor blueprint
6. use the keypress to simulate physics for the actor.
7. Once the actor is simulating physics move the line trace across the child component with multiple materials a couple of times until it crashes.
Results: The editor will crash after line traces across the child component materials after a couple of times.
Expected: The editor should not crash.
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-27544 in the post.