*We recommend staying on macOS 10.13.3*
Installing macOS release Version 10.13.4 will cause Duet Display stop functioning after the OS upgrade. We have alerted Apple to this issue and are working hard to find a resolution. These features continue to work as expected in 10.13.3.
We would strongly recommend contacting Apple though their bug reporting (https://developer.apple.com/
We are actively looking into workarounds so that duet is not affected by the macOS bug, and will keep you informed. Please e-mail us if you have any questions. Thank you for using duet.