In my very limited experience, I`ve had a similar issue. I have built two bows,a longbow and a recurve. Both are around 30#. When I finished the longbow, I had a hell of a time tuning it to shoot straight. It is cut 1/8" past center. I had good grouping, with the occasional flyer, but it just didn`t shoot straight. Tried many things with arrows and arrow rest: sometimes it was better, sometimes worse, but never good. I decided to make another bow, this time a recurve. What do you know? Same issues! That clued me in: the arrows were waaayyy too stiff and were hitting the shelf: XX75 2016 w/ 100gr field points, cut to 28". I then purchased a few weaker arrows (1816 and 1616), and several different point weigths, and found a good working setup. I solved the issue on both bows, but my recurve still needs softer arrows than the recurve, even being 2# stronger (31# vs 29#). So, it really depends on the bow, and probably shooter`s form...but, if your groups are good, you CAN get there...it is just a matter of trying farther away from your usual arrow parameters, and testing methodically. Just my opinion, of course, and, being the newbie that I am, it is probably not worth much anyway, but, if you like the bow, keep thinking about what you can do, and keep testing, and you will get there.
Good luck.
DF