Complex collision mesh might lose its collision in the editor

This is affected by loading order.

In the case, display mesh was loaded firstly and try to build collision mesh form complex collision mesh asset. But the collision mesh didn't finished to make RenderData.

UStaticMesh::ContainsPhysicsTriMeshData returns nullptr, so the display mesh lose the collision mesh.

To Call ConditionalPostLoad on the collision mesh before building the collision on the display mesh can fix this issue.

// code placeholder
bool UStaticMesh::ContainsPhysicsTriMeshData(bool bInUseAllTriData) const 
 {
 #if WITH_EDITORONLY_DATA
     if (ComplexCollisionMesh && ComplexCollisionMesh != this)
     {
         ComplexCollisionMesh->ConditionalPostLoad(); // !!! please add this line !!!
         return ComplexCollisionMesh->ContainsPhysicsTriMeshData(bInUseAllTriData);

1. open attached  [Link Removed] with 4.23
2. (optional) remove all DDC (in Engine/DerivedDataCache foloder) and launch editor with -ddc=noshared
3. start PlayInEditor
4. move forward to hit a wall

Result

Player doesn't hit the wall and does go through the mesh.