poi in fixed sight handguns depends on ammo and distance. using 850fps 230grn fmj in my fnx45t #2 is where my poi is in relation to poa at 15yds. use a lighter faster bullet or a shorter distance or longer or heavier or slower or some combination of those variables from factory test ammo poi will shift.It may be that you are using the wrong sight picture for the FN pistol. In this picture #3 is the correct picture for the FNP/FNX automatics.
If you use #1 or #2 as learned in the past your POI will be low.
most common cause of low poi is shooter error.
to detect what your doing have a friend load your pistol while you are facing away sometimes have your friend load a spent case. the feedback you get when it goes click instead of boom is invaluable for fixing shooting technique errors that the recoil of the gun going off tends to hide.