DRO's are nothing more than counters. They add or subtrack count "ticks" as you move the sensor one way or another.
To get good resolution, they typically have many tiny "ticks" that are read and then divided electronically to convert to in or mm of motion.
There has to be a "decoder ring" someplace to tell the counter what the division ratio is for the tick count coming in to make it read correctly on the screen.
I'd be someplace somewhere something isn't programmed or the gearing isn't matched correctly....