MKS DLC32 Max with DM542T v4 drivers

[Aepx]

First time using a grbl board with external drivers and I'm not having any luck.
I have the drivers connected to the external pins on the controller as follows:
S -- PUL+
D -- DIR+
E -- En+
G -- All 3 grounds for the above

The drivers are set to 5v.
The motors do work but I'm not getting enough torque to move the X or Y axes.
Also, no holding torque at all even though I have $1 set to 255. (BTW, what's the difference between $1=255 and the setting to enable all axes always? (maybe $17? I forget and am not connected right now)

Is there any known issues with the MKS DLC32 Max that would cause this?