Thank you for posting! I am sorry things are not working as expected with your TBT3-UDV dock and I would be happy to help.
An important note - the TBT3-UDV does not use DisplayLink technology, so the DisplayLink driver is not needed.
That said, the behavior you describe is not typical so our next step is to get some additional information. To help us do so, please send the following information to us directly via firstname.lastname@example.org with ‘For ticket # 279326’ in the subject line. This will help us match things up and determine the next steps.
** Please do not post the information we request in our public forum, as it contains personal information **
Is the behavior specific to only the display connected via the USB-C to DisplayPort video cable?
Can you provide the brand and specific model number of the USB-C to DisplayPort cable you mention using?
If you connect the dock to a different Thunderbolt 3 port within your MacBook Pro, does the behavior change?
Can you confirm that the source video input setting within the affected display is set correctly to ‘DisplayPort’? I ask because displays with multiple inputs may not always switch to the preferred one automatically.
Can you provide the Amazon Order ID number for the TBT3-UDV purchase?
While the dock is connected to your laptop and both displays are connected to the TBT3-UDV (even though one is not working), can you provide us with the output of our diagnostic utility PlugDebug? --> http://plugable.com/support/plugdebug This will allow us to examine some log files from your system to help determine the next steps.
Thank you for giving us the chance to help!