https://www.techradar.com/news/apple-macos-10134-renders-key-third-party-display-products-useless

Thousands of Mac users are crying foul at Apple following the release of macOS High Sierra 10.13.4 having rendered key third-party display products and services useless. Particularly, neither DisplayLink docking products nor the Duet Display Mac app are working in this latest version.

A DisplayLink product manager responded to complaints on its own support forums, confirming that macOS 10.13.4 is to blame for the error, and that it’s working on a fix. This update specifically renders the display capabilities of its docks inert, while other functions remain unaffected.