When I put my new short block together, I put the pan and filter on, and cranked it as fast as I could with a breaker bar, after 15 revolutions no pressure, I pulled the plug on the side of the block, there was oil. After 30 turns no pressure, I pulled the filter, there was oil, it took a total of 40 revolutions to get oil pressure. It takes time to fill those oil galleys by the lifters. They have to be full to make pressure. If you let it run for 10 seconds, more than once, and oil has not made it to the filter, there is a problem with the pump.
Sorry, no way to check the pump without turning the crank. If you have ARP main studs, the nuts are taller, that will space the pickup down, if you did not check, it could be on the bottom of the pan. Yea, that happened to me.