Cannot edit collision response details in SkeletalMesh components added via Blueprint.

If the mesh component is added in Blueprint (i.e. in the Blueprint editor and/or through Construction Script), then it's not possible to edit the collision response details for an instance of the component in the level editor when the collision preset is set to "Custom..."

However if the mesh component is native (i.e. added in C++), then collision response editing seems to work as expected.

My guess is that it may not be properly caching per-instance overrides for the collision response flags, so they're not being restored when those components get reconstructed during a RerunConstructionScripts() call.

1) Create a new Blueprint Class based on Actor.
2) Open it in the Blueprint editor and add a Skeletal Mesh component. In the "Collision" details, set the "Collision Presets" property to "Custom..."
3) Compile and save, then close the Blueprint editor.
4) Create another new Blueprint Class based on SkeletalMeshActor.
5) Open it in the Blueprint editor and select the Skeletal Mesh component. In the "Collision" details, set the "Collision Presets" property to "Custom..."
6) Compile and save, then close the Blueprint editor.
7) Drag an instance of both Blueprint class assets into the current scene.
8) Select the instance of the class created in step #1 and select the "SkeletalMesh" component in the Details view. Scroll down to the "Collision" section and note that you cannot toggle any of the collision responses (even though the section is enabled).
9) Select the instance of the class created in step #4 and select the "SkeletalMeshComponent" component in the Details view. Scroll down to the "Collision" section and note that you can toggle the collision responses here.