Did you add collision directly to the mesh (blender/3DSM, SM Editor)?
The mesh has to have it’s own derived collision. You can use a collision component, but it needs to be the Root and the mesh a child. Doing so also means that the collision shape is what will be used for the actual physics interaction.
Furthermore, you need to enable query and physics collision.
You cannot use the “Use Complex as Simple” collision setting.
You also cannot scale down the mesh.
Demo it with a default cube mesh. When it’s working right swap out the mesh.