I have tested this in standalone 5.6 also and found that no simple collisions are auto-generated when creating a cubegrid mesh anymore.
Tested with changing collision presets on the mesh in mesh editor and in level editor.
Went back to validate this was the default behaviour in 5.3 and confirmed that simple triangualted collision meshes were created.
The only solution is to set “Collision Complexity” to “Use Complex as Simple” which isn’t an efficient workaround.
Short of that, manual creation of collision meshes.
