To convert the TBT3-UDV's DisplayPort output to HDMI, Plugable specifies the included active adapter, supporting up to 4K at 60Hz. Converting that output to DVI or VGA also requires an active adapter. A passive product with the same visible connectors is not an equivalent substitute for this dock.

A supported second display can instead connect through the downstream Thunderbolt 3 port using an appropriate USB-C Alt Mode adapter or cable. The host must support that second video stream. Check both the conversion type and host capability before interpreting a blank adapted monitor as a broken output.