Branches not being auto built from GitHub

I am one of the maintainers of an open source project that uses CircleCI. We have a GitHub webhook triggered by a number of events including pull request creation, branch creation and push. That has previously meant that we would have a nice summary from CircleCI at the bottom of all pull requests as expected (here for example).

For the last week or so, pull requests have not had this summary (for example). When I look at the hooks details on the GitHub side, however, everything seems to be triggered as expected. I do not see those branches on CircleCI.

To make matters more strange, my own branches weren’t getting automatically built but then I clicked around the CircleCI app without finding any kind of setting that seemed relevant and my next branch was automatically built. Merges to master are always built and correctly reported through our Slack integration.

We had several days before this started happening of intermittently failing builds because of an issue with a test (our fault).

Any ideas on how to troubleshoot this would be greatly appreciated!

An eagle-eyed contributor noticed that “Build forked pull requests” in the project advanced settings had at some point been turned off. It’s possible that was the problem, I’ll need to report back after we get some more pull requests from branches.