Hello,
Thank you for contacting Rank Math and bringing your concern to our attention. I’m sorry for any inconvenience this issue may have caused you.
To fix the issue, please make sure the service account is listed as the Owner of the site in the Search Console.
Please follow the steps illustrated here to solve the issue:
https://rankmath.com/blog/google-indexing-api/#403-permission-denied
This is one of the most common issues when setting up the Instant Indexing plugin.
If that doesn’t work for you, please remove the plugin, then install and configure it again by following the steps religiously.
Looking forward to helping you.
Hello,
Since we did not hear back from you for 15 days, we are assuming that you found the solution. We are closing this support ticket.
If you still need assistance or any other help, please feel free to open a new support ticket, and we will be more than happy to assist.
Thank you.