I am maybe late but i think i know the problem.

The problem is the yellow rectangle you got there. From my guess that rectangle doesn't contain polygons. What i mean is, you just have a rectangle and nothing more. To fix this problem. Go to it's property and boost the number of spans it has. Give it like 10 or 20 and see what happens.

I'm sure this is your problem. Sorry if i didn't put it in better words. I just can't seem to think right today.