Sounds like a webhook synchronization issue between Vercel and GitHub. Could you try the following:
- Force webhook recreation by going to your Vercel project settings → Git → disconnect the repository, then reconnect it
- Check GitHub App installation - go to GitHub Settings → Applications → Installed GitHub Apps → Vercel, and ensure it has access to your repository
- Verify branch protection rules - sometimes branch protection can interfere with webhook creation
Let us know how you get on!