TBD… I’ve found no standard answer… i.e. trial and error.
I usually just make a copy of the style and experiment with different settings… combined with the background color trick… until I find the right combination.
FYI… if you search Google for blank pages in SSRS… you’ll see it’s REALLY common.
And of course… the Traveler layout is fairly involved, so it could turn out to be a rectangle within another rectangle, etc…
Here is an example of an AP check where I used alternating, colored backgrounds to figure out what was going on. In this case, different component dimensions were based on different parent rectangles… so typing in new coordinates didn’t do ANYTHING like what you’d expect. SSRS…grrrr.