I'm having SO much trouble just getting UGS just to move x and y motors correctly, connected direct to Uno..

Brand new build - NO Breakout board yet - just motor drivers connected directly to pins on Uno.
I know most people use breakout boards, I'm just trying to test to get 2x stepper motors moving correctly when connected directly to the Uno (just in testing, for now. Breakout board will come later).

Here is my setup
New Arduino Uno (original, not clone).
DM542T stepper drivers connected to Nema 23 motors from stepperonline.
Fresh install of GRBL 1.1f - nothing modified. All standard settings from base install.

My testing:
I connect Uno as per below:

Uno Pin 2 - X-axis DM542T - Step+
Uno Pin 5 - X-axis DM542T - Direction+
Uno Pin GND - X-axis DM542T - Step-, direction-, Enable-

All good - x-axis motor moves clockwise and anti-clockwise when jogging X-axis in UGS platform.

So, then I also connect:
Uno Pin 3 - Y-axis DM542T Step+
Uno Pin 6 - Y-axis DM542T Direction+
Uno Pin GND - X-axis DM542T Step-, Direction-, Enable- and Y-axis DM542T Step-, Direction-, Enable-

Now when I jog x-axis forwards in UGS, BOTH X and Y axis rotate clockwise (Y shouldn't be moving).
When I jog x-axis backwards in UGS, the x motor reverses direction, but the y-motor keeps going clockwise. (x axis moving ok, Y shouldn't be moving)
When I jog y-axis either forwards or backwards in UGS, no motor movement at all.

Connecting Z-axis to pins 4,7 for step and direction, no movement at all on z-axis motor - can't control from UGS.

So I can get x-axis to behave, but Y moves with x when it shouldn't, and nothing moves when I try to jog Y, or Z in UGS.

I've checked wiring 100 times, and used shielded cables. Connecting pin 8 to enable+ on either/both drivers makes no difference.
I don't understand what I'm missing.