Once I moved my project to UE 4.12 I’ve met problems with hollow blocking volumes - character can’t be spawn inside it, and it’s really not hollow in result.
Checking / unchecking “Hollow” checkbox produces this log:
LogPhysics:Warning: PHYSX: (..\..\PhysXCooking\src\convex\ConvexHullBuilder.cpp 1116) eINTERNAL_ERROR : ConvexHullBuilder::CreateTrianglesFromPolygons: convex hull has a polygon with less than 3 vertices!
LogPhysics:Warning: PHYSX: (..\..\PhysXCooking\src\convex\ConvexMeshBuilder.cpp 253) eINTERNAL_ERROR : Gu::ConvexMesh::loadConvexHull: convex hull init failed! Try to use the PxConvexFlag::eINFLATE_CONVEX flag. (see PxToolkit::createConvexMeshSafe)
LogPhysics:Warning: Cooking failed, possibly due to verts too close together. Trying again with inflation.