Hmmn. Strange. I tried 4758 and the step jog didn't work. Then I went back to 4746, which worked. But now when I go back to 4748 it seems to be working! So, there's something random going on - could be the crappy FW of course.
I will see how it fares over a longer trial period.
That said - The step jogging is not always precise. I have the increment set to 1mm, and it randomly affects the fractional component too. Not always. I get sequences where the step is exactly 1mm, but then a series of fractional steps.
I can grab some logs if you tell me what you need (and how) - I tried the debug log, but it didn't look useful as it simply shows a jog event taking place with no additional details.