Thanks for contacting us! The graphics port on the Plugable UD-3000 is a DVI-I port. DVI doe not have any support for audio.
If the TV is connected only to the graphics port on the Plugable UD-3000 via DVI or HDMI, audio will not flow through this connection as DVI does not have support for audio.
Although by default DVI-I output that allows you to connect via DVI, VGA (using the passive DVI to VGA adapter) or HDMI (using the passive DVI to HDMI adapter) does not provide the audio signal to the passive DVI to HDMI adapter.
Audio will only flow through an HDMI connection when the default output of the USB Graphics adapter is HDMI. So only video signals will flow to the monitor/ TV connected to the graphics port on the Plugable UD-3000. There are no workarounds for this. Sorry about that!
On the Plugable UD-3000 audio will only flow to a speaker connected to the audio jack if the dock is set as the default audio playback device.
Hope the above information helps understand what you are seeing! If you need any additional information, please do feel free to shoot us an email at support@plugable.com. We are here to help!