I have an FLSun 3D Cube, running off an MKS GEN V.1.4 main board. With Marlin 1.0, the Z-axis works great (and has been for three years). When I try to upgrade to Marlin 2.0, moving the Z-axis 10 mm results in extreme motion -50 mm at least, left motor then the right motor, three or four times, very fast. It's loud, it's jarring, and it's at the very least incorrect.
What setting am I missing?