Question X-axis is strange!!!

When my CNC 600 draws curves or circle, spindle moves about 1mm less along x-axis.
I checked machine assembly, it's okay. whenever my machine is operated at any position on bed, the result is same patterns.
I found a spindle move and stop slightly when it draw a curve or circle.
My computer and machine status are okay but i suspect it come out of communication or stepper motor drive problem.
Does anybody have a similar status to my machine's condition?

thanks..

(the result was same on constant mode or exact mode of UCCNC setting and backlash was no problem on it.)

important to know if its a "moving zero point" or "backlash"...

does the Zero position stay the same?

if yes... then its backlash


if the zero position moves after a job cycle then its lost steps and the X axis needs mechanical tuning

The zero position is always correct.

Can you post a picture of the result from a circle?