Hi Lowell,
Thanks for posting!
We have an updated firmware for the TBT3-UDC3 dock that should resolve this HDMI flickering with the MacBook Pro 16". You can find a thread about it here: https://support.plugable.com/t/monitor-blinking-on-hdmi-port-of-tbt3-udc3-with-mbp-16/20299
If you’re able to update the firmware with a USB-C or Thunderbolt 3 Windows computer, please let me know.
If not, no worries – we can send you a warranty replacement flashed with the latest firmware. Please contact us at support@plugable.com with your Amazon Order ID and we’ll move forward from there.
Thanks for giving us a chance to help!
Mitchell