I have a similar problem, which is a pain for touching off manually. Both the DRO's and actual machine movement is less than that commanded by either Gcode from the MDI or jog - so I don't believe it has anything to do with the controller.
Now running version 4.2.0.3804 (but the problem also existed in versions from May and Sept 2017)
Screenset: stock wx4 from latest download, and in customized wx6 from ~Sept 2017
As this is bugging me, I've done some more tests today to quantify the problem. The table below shows the error for 5 separate executes of a line of gcode via the MDI ie G54 G91 G0 Zstep. For example, if Z0.001 is commanded 5x, the DRO and the machine move in uniform steps to 0.005 (so DRO/5X = 1.000). Same for 0.002mm, but not so for increment values from 0.002-0.098mm. For step sizes above 0.098 mm everything is perfect. Odd, especially as ridiculously small steps work OK.
step
(mm) DRO @ 5X DRO/5X
0.001 0.005 1.00
0.002 0.01 1.00
0.003 0.01 0.67
0.004 0.015 0.75
0.005 0.015 0.60
0.006 0.02 0.67
0.007 0.02 0.57
0.008 0.02 0.50
0.009 0.025 0.56
0.01 0.03 0.60
0.09 0.42 0.93
0.098 0.49 1.00
0.099 0.495 1.00
0.100 0.5 1.00
The jog command will not work at all for step sizes below around 0.05mm, meaning that I always have to use an MDI line of gcode to execute fine jogging.
Note that in all cases DRO changes are accurately reflected in axis movement (using a Z-setter, 0.01mm divisions).
I realise that 0.001mm movements are totally meaningless for machining, but my router/engraver will move 0.001mm on and off the 3D probe repeatedly (Z axis only - so no backlash issues) - despite the use of 1/25th microstepping.
Any ideas please? This is really bugging me.
Best regards,
Louis