Several manufacturers, including Reese, have custom brackets to mount their rails to the F350 that don’t require any drilling in the frame. They use existing holes and simply bolt on. As DaveSchwartz said, they must not have used the custom brackets designed for your truck or simply installed them wrong.
The front rail’s mounting slots are ~57” forward from the rear of my truck’s bed, which leaves the pin an inch or two forward of the truck’s axel. As you surmised, your rails aren’t properly mounted.
My truck is a single rear wheel F350 long bed with Air Lift air bags. It was a little tricky mounting the rail brackets with the already air bags installed. Your air bags may present a problem with mounting the rail brackets. You might need to contact your air bag manufacturer to ensure compatibility.
Since the hitch given was a Reese, the rails are most likely Reese rails but not necessarily. As biznsa recommended, contact Reese, a local hitch installer or perhaps etrailer for advice.
It may be best to install custom brackets from a new rail kit and avoid further drilling in the frame as well as the delays trying to make do with the existing kit can cause.
2015 Wildcat 282 RKX
2011 F350 Lariat, 6.7 L. Diesel, 8 ft., SRW, Reese R20