After upgraded from Big Sur to Monterey, my MBP has issues with Motu audio driver, especially when using Video Chat apps. The audio driver crashes when video chat app launches, without any sound playing out at all. The console has such crash log for the MOTUCoreUACAudioServerPlugin:

abort() called
terminating with uncaught exception of type boost::exception_detail::clone_impl<boost::exception_detail::error_info_injector<std::runtime_error> >: buffer key already exists in the map!

Googling around doesn’t help much. The above log suggests that the app is launching audio twice, leading the output audio driver to clone the same buffer, which is quite mysterious.

Fortunately, Motu USB audio interface actually can work without the driver, just as a common USB audio device. The only side effect is losing the loopback interface in the DAW. After some test of unloading the driver kernel extension, it does work well with the video chat app as a pure USB audio device.

Because Motu doesn’t provide driver uninstall program, the only way is manually removing it. This guide shows how to use systemextenionsctl to uninstall the driver from MacOS, as deleting kernel extension files won’t work. Make sure disabling SIP temporarily beforehand.

Hope that Motu will release newer driver fixing the crash problem.