The Dir LED will only be on when moving one direction, and off for the other direction. It's just a 0V, or 5V signal, depending on direction.
So, if the Step LED is not lighting up, then the UB1 is probably not sending any steps.
You said you have an emergency button wired to Y104? If you push the button, does UCCNC go into Reset?
I think I was mistaken about the OVR button. I think you only need it if you are using the OSSD output. The OSSD output should turn off when the safety circuit is triggered, and the OVR button turns it back on.