Hotkeys fail to register

MBP with attached monitor, and a PC with dual monitors.

I have set up a hotkey to move to the next screen by screen name. Nothing happens when I activate the hotkey.

I have tried every combination of 'when pressed,' 'when released,' and every combination of different hotkeys, or using move to left instead of move to specific monitor.

I was originally getting a "WARNING: Keypress (xxx) failed to register"

Any thoughts on what to try next?

Thanks