I assume you mean your broadheads are not shooting to the point of impact as field points. This is pretty common. As for tuning, you may think your bow is perfectly tuned, but it isn't. Porpoising is usually a sign of an improperly located nocking point or underspined arrows. In your case it sure isn't an underspined arrow.

I'm guessing that by tuned you mean shot through paper and getting bullet holes. OK, paper tuning is just a rough place to start the tuning process. It tells you how your bow is leaving the bow, but tells you nothing about what is going on down range. This is where broadhead tuning can help. And when paper tuning you need to check it at several distances. If you are tuning for a bullet hole at a particular distance it si tuned for THAT distance only. Move the paper a few more feet away and it may show a different result. And much over about 10 yards doesn't mean squat as the fletching is taking control by then anyway. That's just one reason I consider paper tuning a waste of time.