I meant to put the triggering code into the BeginPlay of something else. I would have thought spawning the actor from within it’s own BeginPlay would have led to recursion problems.
Anyway, I’ve attached the code (on the original question) as I have it. This is all I’ve added to a blank project, along with the level blueprint set up as shown to trigger the spawning. No need to place an instance of the actor by hand.