TBT3-UDC3 blinking monitor

Brand new dock plugged into brand new 16" MacBool Pro with Big Sur. I have two 32" Samsung monitors connected via hdmi cables (with the second using your supplied DisplayPort adapter).

If the computer goes to sleep, when I wake it up, the monitor plugged into HDMI blinks off for 2 seconds and on for 2 seconds and repeats forever. During this time nothing affects it. I’ve reseated cables, restarted the doc,

The only thing that works is a restart of the entire computer.

Please help.

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!


Hi Mitchell,

I saw this thread too! But I don’t have a windows computer. Only this MBP 16".

Understood! Please just reach out to us directly at support@plugable.com and include your Amazon Order ID.

We’ll confirm purchase and warranty status and move forward from there with a replacement.



While the firmware update might help, I suggest you make sure both display outputs are set to 60Hz max in System Preferences>Displays. Any higher setting will cause issues on my system…

I bought this via Walmart online. ??

Thanks for the note, @eysun!

@str11ngfello, in that case, please feel free to provide the Walmart order ID or invoice in the email to support@plugable.com.

Thank you!


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