Permissions error fetching application - Gcloud app deploy

I am trying to deploy to a gcloud app (following the steps here: https://realpython.com/python-web-applications/). My gmail account is the owner of the project (and just to be safe, I've added lots of other roles like app engine deployer, viewer etc even though I think owner should cover all of them). When I enter "gcloud app deploy" I am getting the following error:

ERROR: (gcloud.app.deploy) Permissions error fetching application [apps/hello-app-389902]. Please make sure that you have permission to view applications on the project and that XXXX@gmail.com has the App Engine Deployer (roles/appengine.deployer) role.

I've tried re-authenticating, adding more roles and I keep getting the same error. I've googled but none of the solutions posted there worked for me

1. Confirm you're trying to deploy with the right account. Execute the command

   gcloud config list account to get the current account (email) that you're deploying with.

2. If the above is not the right email you're expecting, then set the right account (email) by executing

   gcloud config set account <email>

3. After executing steps 1 and/or 2 above, open a new shell/command prompt and then try deploying again (the key here is to try it again in a new shell/command prompt)

Billing services were not enabled. Enabling billing services fixes this error