Github action not caching node_modules across jobs

I have a Github action on pull_request, and am attempting to cache node_modules between jobs. I can only see cache working on a job re-run, but not when opening new PRs, even when there have been no changes to my node_modules.

Is this by design?

Each time it runs in a new PR, I see this output in the job:

Run actions/cache@v2
  with:
    path: ~/.npm
    key: Linux-build-cache-node-modules-83fc6365b85dd061416fccd5993d48c2003c388bb2184fd57f28d1041d9d261e
    restore-keys: Linux-build-cache-node-modules-
  Linux-build-
  Linux-
  
  env:
    cache-name: cache-node-modules
Cache not found for input keys: Linux-build-cache-node-modules-83fc6365b85dd061416fccd5993d48c2003c388bb2184fd57f28d1041d9d261e, Linux-build-cache-node-modules-, Linux-build-, Linux-

Yet, re-running the job will enjoy the cache hit:

Run actions/cache@v2
Received 54525952 of 109978126 (49.6%), 51.8 MBs/sec
Received 109978126 of 109978126 (100.0%), 67.8 MBs/sec
Cache Size: ~105 MB (109978126 B)
/usr/bin/tar --use-compress-program zstd -d -xf /home/runner/work/_temp/0bdf436d-9d4d-4397-b8ed-5910ff503949/cache.tzst -P -C /home/runner/work/argutopia/argutopia
Cache restored successfully
Cache restored from key: Linux-build-cache-node-modules-83fc6365b85dd061416fccd5993d48c2003c388bb2184fd57f28d1041d9d261e

Here is my action yml for reference:

name: PR CI
on:
  pull_request:
    branches: [main, develop]
jobs:
  build:
    runs-on: ubuntu-latest
    strategy:
      matrix:
        node-version: [14.x]
    steps:
      - uses: actions/checkout@v2
        with:
          fetch-depth: 0

      - name: Use Node.js ${{ matrix.node-version }}
        uses: actions/setup-node@v1
        with:
          node-version: ${{ matrix.node-version }}

      - name: Cache node modules
        uses: actions/cache@v2
        id: cache
        env:
          cache-name: cache-node-modules
        with:
          path: ~/.npm
          key: ${{ runner.os }}-build-${{ env.cache-name }}-${{ hashFiles('**/package-lock.json') }}
          restore-keys: |
            ${{ runner.os }}-build-${{ env.cache-name }}-
            ${{ runner.os }}-build-
            ${{ runner.os }}-

      - name: Install Dependencies
        if: steps.cache.outputs.cache-hit != 'true'
        run: |
          echo '::debug::deps cache miss - installing deps'
          npm install