Zero integrations available while creating the Integration target proxy in APIGEE

We have created a couple of integration in the Integration portal but was not able to develop the Apigee Integration target proxy in Apigee X. It's showing 0 integrations available while creating the Integration target proxy. For roles, I have assigned service-GCP_PROJECT_NUMBER @gcp-sa-apigee.iam.gserviceaccount.com to Apigee Integration Admin, Service Networking Service Agent, and connector admin but still, it shows 0 integration available while creating the integration enabled proxy in Apigee X.