1 Answers
I think there is a limit on the number of projects that can be attached to the billing account. (Billing enabled on 3 I believe)
List your billing accounts: gcloud beta billing accounts list
List projects connected to billing account: gcloud beta billing projects list –billing-account "billing-account"
If you have 3 or more try deleting projects from the list
To link a project to a billing account:
gcloud beta billing projects link "project-id" –billing-account "billing-account"