Thank you for contacting us, I am sorry this is not working as expected and I am happy to help!
Based on your description I would like to start by fully resetting the docking station and computer to see if this helps to restore connectivity for the external displays on HDMI 2 and HDMI 3, please perform the following when you have a moment:
- Disconnect the docking station from the computer and remove the power connection from the back of the docking station, unplug all USB devices from the docking station
- Disconnect the docking station’s power supply from the wall and let both the docking station and power supply sit for 30-90 seconds to fully discharge
- Restart the computer
- In macOS: Apple Menu > Restart
- After 30-90 seconds, reconnect the power supply to the wall socket or power strip
- Reconnect the power supply to the docking station
- Verify the blue power LED is illuminated on the front of the docking station, please let me know if this does not come on when connected
- Reconnect the docking station to the computer
- Please be sure to use the original USB cable provided with the docking station
- Connect the cable directly from the docking station to the computer, adapters, hubs, or cable extensions may reduce the docking station’s capabilities or prevent detection
- Check for the external displays to be detected on the system, if they are not detected please let me know
- Reconnect USB devices to the docking station one at a time, test each device to make sure it is working before connecting the next device.
Please let me know if this helps, if not we can reinstall the latest DisplayLink Manager for macOS ( released today: 2021 June 2nd ).
Thank you, I look forward to your reply.