Can't connect to inbuilt audio cubase 12

Monterey 12.2
Mac Book pro 14 in 2021
cubase pro 12.0.20 build 263

For some reason I can’t connect to inbuilt audio - it is selected as the ASIO driver in Audio System - it also appears as a drop down audio device option in output and control room in audio connections - when I try and select it it reverts to not connected - It was working fine yesterday so I am not sure what I have done wrong.
I was using Dorico this morning but that is closed down and I don’t think there is anything else running that might need and audio driver