title: Unkown failure to associate VPC connector in service project with shared VPC subnet in main project
body: <p>When trying to associate a VPC connector in a service project with a shared VPC subnet in another project (From the same organization) the following error appears:</p>
  <pre><code>Unknown error. Original error message: Operation failed: VPC Access did not have permission to resolve the subnet or the provided subnet does not exist.
  </code></pre>
  <p>We tried past what is acceptable for permission propagation as pointed in this other post:  <a href="https://stackoverflow.com/questions/58693160/gcp-shared-vpc-a-subnet-is-not-shared-from-host-project-to-service-project">GCP Shared VPC : a subnet is not shared from host project to service project</a>, we definitely waited more than 20min and the error persisted.</p>