Edits to TriggerBox 'Shape' parameters (in a ChildActor component) only update in Blueprint Viewport once, to view subsequent updates one must re-open Blueprint.
Confirmed in 4.22 MAIN - 4631879
Result: The change in value will be reflected in viewport the first change. To view any subsequent changes you must reopen BP
There's no existing public thread on this issue, so head over toAnswerHub just mention UE-67284 in the post.