I would start by putting on string loop or metal D loop and retune. I would say that the release under the arrow is the reason you are having issues. These newer bows are just not that forgiving of this syle of shooting. If you can picture this in your head. Your arrow is actually setup that way because of the lack of a D-loop. You are drawing from the center point (release in the center of the string if the nock is high). The nock is high, the tip is starting low. It isn't a huge angle but it is an angle (on the arrow at full draw) you need to get a loop and square your arrow/rest up and try again.

Also, before you change everthing, did you have this issue before tiller tuning?

I am sure you will get more/other/even better advice. This is just mine.

Good Luck.