Add Project not working after Repository Transfer

I recently transferred GitHub repositories from one user to another, then deleted the old account. After which, the repos stopped building. So, I attempted to add them again under the new account. I cannot do this, as it hangs at the screen, or adds it about an hour afterwards, but does not pick up and new commits. These repos were being picked up before by CircleCI, so they have not changed.

I also created a new repo (of an entirely new name from any others) and it is not being picked up either.

Thanks for any suggestions.

Some extra details…for projects that I am able to add, when a new commit occurs, the github webhook is returned a 500 error from circleci:

{"message":"An internal server error occurred."}

I just tried removing the projects and re-adding. All works now.