I have both VS on my Mac build and Windows 10 machine set to the stable release. The Mac often though for iOS is out of sync, so I can't talk to it.
If I allow Windows VS to force the Mac to downgrade to it's version of iOS, then the Azure Build Agent on the Mac stops working.
The Xamarin.iOS SDK version '126.96.36.199' that is installed on the Mac is not compatible with this version of Visual Studio. Would you like us to install Xamarin.iOS '188.8.131.52' for you? This will overwrite any other existing Xamarin.iOS installation on your Mac.