So the workaround is to set a flag when “Event Receive HitBox Begin Cursor Over” (and clearing said flag on cursor out). Then when LMB pressed triggers, test first whether the mouse cursor is over a HUD element by testing the flag, and if not only then continue with checking for objects in the world being clicked. Of course if, like most game engines, cursor out fails to trigger correctly on occasion due to rapid movement of the mouse over several HUD elements, then clicking in the world is going to be ignored until the player moves over and out of a HUD element “correctly”, so this is not a clean solution.