Manually running pipeline freezes when multiple branches are used for same pipeline

I can't seem start pipelines from a feature branch.
I started the pipeline by going to the branches view and choosing run pipeline for a branch. Whenever I try to run pipelines this way, the build doesn't start. It hangs on this screen:

I'm on the bitbucket_pipelines branch. My bitbucket-pipelines.yml looks like this:

#!yml

pipelines:
  branches:
    '{master, develop, bitbucket_pipelines}':
      - step:
          name: Build
          caches:
            - bundler
          script: 
            - ruby script/setup_pipeline_configs.rb
            - bundle install
            - bundle exec rspec