Always getting Error: Bad response: 422 {"message":"Couldn't find a repository matching this job.","error":true}

Trying to use a private repo with the github action using the following .yml:

on: ["push", "pull_request"]

name: Test Coveralls

jobs:

  build:
    name: Build
    runs-on: ubuntu-latest
    steps:

    - uses: actions/checkout@v1

    - name: Use Node.js 10.x
      uses: actions/setup-node@v1
      with:
        node-version: 10.x

    - name: npm install, npm test -- --coverage
      run: |
        npm install
        npm test -- --coverage

    - name: Coveralls
      uses: coverallsapp/github-action@master
      with:
        github-token: ${{ secrets.GITHUB_TOKEN }}

this is the exact same .yml provided on https://github.com/coverallsapp/github-action as the "standard example" with make test-coverage swapped for npm test -- --coverage (to generate lcov.info).

I've logged into the website and turned the repository "on" and I see the repository in the "my repos" tab, but still the action always fails with the following:

I'm kind of stumped, are there some better docs to take a look at or any working examples?

Start with the workflow YAML and the coverallsapp/github-action@master step, then inspect how GITHUB_TOKEN and private repositories are handled. Reproduce the failure with the provided workflow and lcov.info, and compare it with the action documentation or working examples. Done means the action can locate the private repository and submit coverage successfully.