Hierarchical Instanced Static Mesh (HISM) not rendering in 5.5.1 until Editor UI is clicked

If you guys are stuck using Blueprints, you could also possibly use another workaround where you delay by a frame or two before you start updating the transforms. I think a Delay with value 0 after you’ve added all your HISM instances ought to do it. Small 1-2 frame delay should go unnoticed for the most part.