CircleCi Not Updating PR With Build Status On

We are noticing in several projects we have on GitHub that CircleCI is not posting the build status of PRs. The builds are being run, but CircleCI is not updating the PR with the results. This seems to have suddenly stopped working without us making any changes. I checked the “Build forked pull requests” setting under Advanced Settings and it is set to “On”. Anyone have any idea what may be going on?