Can't get a new project to build on a non-master branch only

I’m evaluating CircleCI for our organization and I’m trying to set up an initial config.yml for a non-master branch. I’ve committed the file to the repository on GitHub, but CircleCI attempts to build the master branch, not the branch I committed and pushed to. The workflow interface doesn’t show the existence of any branches in the project besides master (there are several)

I haven’t added config.yml to the master branch, and I don’t want to.

Any way you can anonymize your config.yml and post it on pastebin or something alike so we can take a look and be able to help?