Could you please check the following things:
- Go to your GitHub org -> Settings -> GitHub Apps -> Azure Boards -> Re-Configure Check that your target repository is listed. Switch to Only select repositories, save, then switch back to All repositories as this can refresh the app’s permissions.
- If the repository is private, make sure the Azure Boards GitHub App has access.
- Go to Azure DevOps -> Select your Project -> Project Settings -> Service connections -> Ensure a GitHub connection exists and is authorized.
- Make sure your Azure DevOps identity email matches the GitHub user email. You must be a member of the GitHub org, and your GitHub email must be public or verified.
- Paste the PR URL in the browser to confirm and also ensure that PR is in active state or merged and it is not from forked repo.
Hope this helps!
Please Let me know if you have any queries.