Thanks for reaching out! Can you please provide some more information as to how the Headphone or System Output zone does not play? Do you see any error messages displayed? Do you have any active firewalls on the affected Mac? Is the behavior the same if you try to temporarily disable any active firewalls?
On your Mac you can configure two different output devices: the standard device which uses the mixer (Standardgerät) and output via Coreaudio, which in the device setup should be configured with the ‘Exclusive mode’. This is the only device you should enable in Roon. You can use it both for playback from your Mac’s speakers and for digital Toslink output from the Mac’s headphones output, if your Mac model supports Toslink out.
I can see that you have both devices enabled with the same Roon device name. I don’t know if this causes any problem, but I suggest to disable the standard device or at least rename it.
Other than that, I am not sure what might be Microsoft Team Audio’s role in that, even if you haven’t enabled it in Roon. It seems to make use of Coreaudio, and if Microsoft Teams software is running on your Mac, it may take exclusive control of the Coreaudio device and prevent Roon from accessing Coreaudio.
Thank you for that additional information. Can you please reproduce the error, note the exact local time + date + track when you tried to play in Roon, and let me know here? I can enable diagnostics mode for your account afterward. Also, did you use any backup software to restore one Mac to another, apps like Time Machine?