That’s quite interesting. Transfering the project more than likely resulted in an issue with the webhook (unless you created a new repo and manually pushed the code).
Could you try completely removing the project from CircleCI, ensuring the Webhooks are deleted from the project on GitHub, and re-add the project?
This will refresh all permissions and Webhooks. That should resolve the issue for us.
If this does not work, please feel free to submit a support ticket and we’ll be happy to investigate further.