Pocket not being cut to the correct depth

trying to cut a pocket I set my cut depth to .250 and it is cutting to a depth of .185. I tried to add the difference and nothing changed it still just cuts to the depth of .185 what could I be doing wrong or what could be causing this issue

Does it cut to the correct depth when previewing the code?

If so, check z-axis belt tension, pulley set screw and end mill sharpness