I have the same problem with my HP UltraSlim 2013 docking station. As the display port on the docking station is DP 1.2 the U4919DW didn't recognize the docking station. I have also tried to follow the U4919DW instructions to try to change the DP from 1.4 to 1.2, but the option was not even available after holding the button for 10 seconds. The instructions for HDMI to change from 2.0 to 1.4 seem to work, but the option for the Displayport doesn't work. I think this requires a firmware update to make this work, as the current firmware just doesn't allow the display port to be changed from 1.4 to 1.2. Hope this makes it clearer for the DELL team to understand the main issue.