Trouble resolving components in a xamarin build

I get this these issues in the build:

/Library/Frameworks/Mono.framework/Versions/4.8.0/lib/mono/xbuild/14.0/bin/Microsoft.Common.targets: warning : Reference 'Facebook' not resolved
/Library/Frameworks/Mono.framework/Versions/4.8.0/lib/mono/xbuild/14.0/bin/Microsoft.Common.targets: warning : Reference 'Xamarin.Auth.iOS' not resolved
/Library/Frameworks/Mono.framework/Versions/4.8.0/lib/mono/xbuild/14.0/bin/Microsoft.Common.targets: warning : Reference 'HockeySDK' not resolved
.0/lib/mono/xbuild/14.0/bin/Microsoft.Common.targets: warning : Reference 'HockeySDK.iOSBindings' not resolved

Turned out to be an issue of missing dependency restore step:

I resolved the issue by adding a build step to restore xamarin components.

If you use Xamarin Components in your project, make sure you have the Xamarin Components Restore step in your workflow, and before that the Xamarin User Management step, which handles the auth/login into Xamarin services.