Dro not the same as what is in the gcode.

[dazp1976]

Could it be the backlash in the machine?.
Say, if you've moved the axis in one direction then told it to move the other straight after to measure it.
Any backlash would cause a slight delay in motion. Thus resulting in moving a lesser amount mechanically than what is on the screen.

Or.
Are you saying you want it to move in the minus- direction but dro is showing positive direction (-0.100 vs 0.996)?.
In which case, do you need to reverse axis direction active state?.