Hello all, new to forum so apologies in advance for anything out of sorts.

When conducting a pocketing operation with a .25 endmill the machine changed depths (.015 to 0.25) on its own whilst still displaying set depth (.015). I doubled checked the setup software (aspire 9.519) with nothing being off, I then flipped the material to side b, ran the same program/same setup, same X/Y/Z, and same endmill and it came out flawless.

New material, same program & setup and same error occurred, depth error whilst display did not change.

New material, all new program (aspire), same error occurred yet on a different toolpath (profile cut) and different endmill (.125).

Owner said it was salvageable so flipped to side B, same program. After selecting G code and program start, gantry moved from set X/Y to X-2" (on its own) and proceeded to cut the program and ruin the material.

Auto-Z has been off-broken-disabled for a while (previous cnc tech) so I have been doing it by hand/eye/flashlight but this error occurs after initial Z has been set and locked into Mach-3