According to the manual there is a check ball before the oil goes through the head and the flow of oil is:
Oil Pan -> Oil Strainer -> Oil Pump -> Oil Filter and then into the main gallery in the block before it hits a check ball and then goes into the head. If the oil was going to stop it would, I think, stop at a stuck/sticky check ball. I might give the airline a blast through the oil filter connector as this is closer along the oil route.........unless someone knows better?