Multidisplay not working

I can't get the new Input System to work with Multiple displays.

The setup:

• Unity 2021.3.2f1
• Input System 1.3.0 and 1.4.2 (neither work)
• Windows 10
• 7 Displays
  
• Works in the Editor
• Does not work in the build
• All mouse input goes to the first display
• I am using InputSystemUIInputModule, not StandaloneInputModule

Things I've tried:

• World Space, Screen Space--Camera, and Screen Space--Overlay Canvases, one per Display
• A single World Space Canvas covering all displays
• Changing InputSystemUIInputModule.PointerBehavior
• Having a separate MultiplayerEventSystem for each screen rather than a single EventSystem
• All permutations of the above.

The mouse works in the legacy input system but touch doesn't. I've switched over to the new system hoping it will work with touch, but I can't seem to get even the mouse to work.

Any thoughts would be much appreciated!

 

To clarify, this is with the UnityEngine.UI.

I still haven't found a solution so I'm going back to the old input system and hacking something up for multiple touchscreens.