When upgrading the DisplayLink Manager Graphics Connectivity App to new version within a macOS system, the update process will cause the older version of the App to quit. As a result, any monitors connected to a DisplayLink-based USB video adapter or docking station will stop working.
The solution is to manually start the new version of the DisplayLink Manager Graphics Connectivity App by double-clicking on the App's icon within the macOS 'Applications' folder within the macOS Finder. This will restart the DisplayLink Manager Graphics Connectivity App, which in turn will enable any monitors connected to a DisplayLink-based USB video adapter or docking station to start working again.
Note: The information above is only applicable to the new DisplayLink Manager Graphics Connectivity App. This information does not apply to the older 'legacy' version of the DisplayLink driver for macOS.