The behavior described by both posters suggests that the macOS display persistence cache may be out of sorts.
A way to test this theory would be to clear the cache, aka reset the screen layout.
The easiest way I have found to do this is by using a feature built-in to the DisplayLink Support Tool utility -->
https://www.synaptics.com/products/d...s-support-tool
1. Disconnect all of the external displays from the host
2. Download and launch the DisplayLink Support Tool application.
3. Click on 'Advanced' within the application's menu bar, and then click to select the option 'Reset screen layout'.
4. If prompted, enter your account password and click 'OK'
5. You should receive a confirmation that the screen layout was reset, and a prompt to reboot the host. Click on 'Reboot'
6. Once the system has been rebooted, reconnect the external displays. Since the layout has been reset, you will most likely have to adjust the display settings to your preference.