I have noticed that in 4.18 and 4.19 changing the transform translation via the details in the actor in the editor will cause CreateSceneProxy to be called. Using the viewport gizmo to drag translate does not cause CreateSceneProxy to be called.Why?

In 4.17 this was not a problem. Also in 4.18 and 4.19 using the viewport gizmo to drag translate does not recreate the scene proxy and is not a problem. However, an actor with a large mesh component that takes some time to create will cause a stall when it get recreated.