There was a previous post about this from 2016 (which I answered) confirming this indeed does not work even now in Cubase 10.5.,
OS: Mac OS 10.15.6
Hardware 16" MacBook Pro, late 2019
Cubase Pro 10.5.20
See attached screenshots.
Started with the default mastering template and disabled the effects.
added a second stereo output to the grace m920 - but it did not matter - only ended up using the first stereo output from the template
added the utility tool to the first stereo bus to generate a sine wave
With the grace m920 selected as the audio device, there is no output displayed on the meters with the test utility plugin on the stereo output buss generating a sine wave. But if you change nothing in this project except for switching the audio device to be the built-in output on the Mac, the meters then show signal (and it is audible). I see no indication in any of Cubase’s device or audio settings windows that something is wrong and/or the connection does not work with the m920. I would also expect the stereo output buss in Cubase to still show signal level from the test oscillator even though there may not be any sample rate lock with the m920. Yet there is only signal visible on the output buss when you select the Mac’s built in output (which seems counter-intuitive signal flow wise), i.e., it makes you think there is something wrong software wise with how the mixer is configured.