I have a user with a Dell Precision 5540 Laptop, a Dell WD19-180W dock, two Dell P2719HE and a  U4320Q. 

The P2719HE monitors are connected via Display Port on the dock. When I connect the U4320Q monitor to the HDMI port of the dock, the highest resolution it will find is 720X576. 

If I connect it to the HDMI port of the 5540, it will show up with the resolution of 1920x1080 but the screen stays black. 

I have used Dell Command Update to make sure that the firmware is all up to date. 

I have powered off the 5540 and the WD19 dock, with no change. I'm trying to figure out what step I have missed to get this new monitor to work wit this setup. 

Any insights would be appreciated.