build preparation hangs indefinitely

[GergelyKalmar]

Builds for the following pipeline hang indefinitely at 'discovering any new versions of pyorbs-release' with 'waiting for a suitable set of input versions' - pyorbs-release - no versions available.

The pipeline is as follows:

resources:
  - name: pyorbs-release
    type: github-release
    source:
      owner: wbrp
      repository: pyorbs

jobs:
  - name: docs
    plan:
      - get: pyorbs-release
        version: every
        trigger: true

      - task: make-docs
        config:
          platform: linux
          image_resource:
            type: registry-image
            source:
              repository: ubuntu
              tag: 16.04
          inputs: [{name: pyorbs-release}]
          run:
            path: bash
            args: ['-c', 'pwd; ls']

The repository is public and does have an existing release: https://github.com/wbrp/pyorbs/releases/tag/v1.0.0

Any ideas what is happening?