Seems linuxcnc has bug with speed

I saw this problem in the past but never write about it.
I have axis Z, that is much slower then other X and Y axes. Z has max speed only 22mm/s. Other axes are much faster.
Everything works fine at first time. But after some time of milling process, I see that axis Z become very fast. It stalls simultaneously at that
time and lost coordinates. I can move Z axis in this new regime and look how it behaves. It moves very fast and when I use G0 movement it similary stalls.
If I turn off/ turn on axis it works fine, but also for some time.
I use G1 movement up but in that time it doesn't work.

I have 2.17.12 linuxcnc version. Today i upgrade it and will look if I solve my problem.
What it could be? Could be problem in the stepper drive?

It does sound like a setup issue if some kind, can you post your hal and ini files that exhibit this problem?

Its very unlikely to be LinuxCNC version related

Most probably missing

setp stepgen.2.maxvel [JOINT_2]MAX_VELOCITY

If using steppers or similar limit for servo.

Yes, you are right. I've added that lines to custom file.

Even without setp stepgen, after upgrading software I finished my detail without problems. As I said earlier, at first time all goes fine but after few minutes, axis Z become very fast. I hope this problem will never return.