Did you get fit for the shaft selection? Titleist has dozens of R-Flex shafts, many at the base cost, to choose from that can optimize launch angle, from Low to High launch. Shafts are much more complex that just R/S/X flexes now.

If you’re not getting shot height with the AP1s, then it’s your swing rather than the clubs. You should consider a lesson or two with a reputable golf professional.

I've had the same clubs for about 6 months now and am around a 17 handicap... no issues and have seen my irons get more consistent. Prob your swing

Assuming your ball position (relative to stance) is reasonably correct the issue may very well be the shaft- as Don suggests having the proper shaft for your swing is not as simple as looking at the flex the shaft manufacturer has assigned to that shaft- there being no standards in the golf industry another manufactures might consider that shaft to be stiff and a third shaft manufacturer may designate that shaft to be a senior shaft. Thus, the importance of being properly fitted.