I'm running a Trigorilla Pro board under Marlin 2.0.7.2 on an Anycubic Predator delta.
I've changed the original microswitch z probe to a nozzle contact piezo sensor, and all is well BUT:

When I do an auto calibration, the printer loses track of where the x and y positions are. The first few probes go fine, then the LCD display indicates that it is moving to say, X=0, Y=-152, and it visually moves to something completely wrong. Of course this confuses the process, and the results aren't pretty. Usually I just get a "Probe Error".

I am sure that the motors are not skipping steps. The firmware just seems to make assumptions about where 0,0,0 is at random during the calibration process. I can manually move the effector using either the LCD or Repetier to any position very accurately, but the firmware apparently cannot.

Any thoughts?