Hello,
If you are running Catalina 10.15.4 please make sure to install this driver:
https://www.displaylink.com/downloads/file?id=1552
Also once you install it - or if you already have it installed:
Make sure that you run the DisplayLink Manager when you log in to the user where you screen is not working correctly. The application works per user, not per system so each user has to have it turned on manually.
If by any chance you cannot start DisplaLink Manager on the second user make sure to close it on the original one where everything works. You can close it in the right top corner of your screen - you will see monitors icon, if right-clicked it will give an option to
Exit.
Then, return to the second user and start the application there.