It almost sounds like a setting for the z axis is wrong for your material. I’d look at that first and maybe check out a homing switch on the Z axis too if you have one.
$132
GRBL_Settings_Pocket_Guide_Rev_B.pdf
Also you may want to look at the gcode to see if there is a syntax error there. Lastly could it be electrical interference? [Solved - Elec. Interference] - Job keeps failing in easel - Easel - Easel Community Forum