You mean your machine is out of position and mach is reporting in position?
Sounds like lost steps, what is your machine, which drives, motor tuning settings?
If steppers. They will take some time to setup correctly, and in a way that they are always reliable.
I run mach 7 days a week, often more than 12 hours a day, and we don't lose position.
More information required, then we can do what we can to help you.
Wayne....