Hi guys (my first post)!

I'm having issues with my CalDigit USB-C HDMI Dock. Screen connected to the HDMI port next to the Thunderbolt 3 port experiences random flickering or stuttering when MacbookPro connected to the dock came from sleep state. Flickering seems to be triggered by mouse movement, see video:


Here's how the issue happens:

  1. Recently started from reboot or OFF state MacbookPro is connected to dock.
  2. Close lid to use in clamshell mode
  3. Use dock with both external displays without any issue.
  4. Disconnect MacbookPro from dock, and let it sleep/hibernate for about 5 hrs. (maybe less)
  5. Come back to dock and reconnect (did both ways; clamshell or open lid)
  6. Flickering issue starts to show on display connected to HDMI port next to Thunderbolt 3 port
  7. Moving the mouse (or trackpad) seems to trigger the issue sometimes (see video)
  8. Issue doesn't go away until MacbookPro is rebooted

Things I tried:

  • connected each screen to that one port and both experienced flickering (the screen connected to the HDMI port left to power supply did not flicker)
  • Reset NVRAM, SMC
  • disconnecting dock from power and reconnected
  • Disconnecting both HDMI monitors
  • "Detect Displays" in Settings
  • Changed resolutions/refresh rates
  • Mirror and un-mirror displays
  • bought 2 new HDMI that support 4ka t 60 cables and the issue persists.
  • new CalDigit dock unit (this is my second unit)


  • MacBook Pro (13-inch, 2017, Two Thunderbolt 3 ports) 2.3 GHz Dual-Core Intel Core i5
  • Big Sur 11.3.1 (20D91)
  • x2 Asus Displays VP239 HDMI 1080p @ 60GHZ
  • New HDMI cables that support 4k at 60GHZ
  • CalDigit USB-C HDMI Dock

Any ideas what it could be? I appreciate your help!!!!! 😩


2 Answers 2


I had the same issue. I installed the firmware update and restarted.
So far so good, maybe it will help you as well.


  • 1
    Sadly no firmware update for USB-C HDMI Dock yet Commented Jun 28, 2021 at 17:45

I had the same issue and was able to get it working using the Windows Firmware Updater tool. Unfortunately you need a Windows laptop with a USB-C port to run the updater, there doesn't seem to be a mac version.

  1. On a Windows computer, go to https://downloads.caldigit.com/

  2. Expand the USB-C HDMI Dock section

  3. Download the Windows Firmware Updater:

    USB-C HDMI Dock firmware updater link

  4. Run the utility. Note that you'll need to connect one HDMI monitor to the dock in the HDMI port closer to the power cord as shown in the utility. This doesn't seem to affect the monitor in any way, but a connected monitor is required for the update to start.

    Firmware updater utility screenshot indicating HDMI port

  5. When the firmware update finishes, power cycle the HDMI dock.

This fixed the one-monitor flickering issue and now both ports are working as expected.

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