Recently moved my setup (Cubase AI / UR44) from a Mac running Sierra to a newer computer running Mojave. Everything worked fine on Sierra MAC but having some issues on newer Mojave MAC. For example, whilst all MIDI ports on UR44 are working fine, none of the UR44 audio inputs/outputs are working within Cubase 10 AI. However, UR44 audio input / output does work properly in Adobe Audition on Mojave computer. Have downloaded and updated to latest version of Cubase and USB drivers. Mojave is up-to-date. Still no joy. Any clues on how to fix this would be appreciated.
A search on Google brought me here for the same issue. Hopefully you got this resolved by now, but if anyone else finds this in the future you have to allow Cubase to access your mic in System Preferences:
System Preferences -> Security & Privacy -> Microphone -> Check box for Cubase