Workflow runs on pull request but not pull request target

I understand that the pull_request_target event behaves in an almost identical way to the pull_request event. However, when I push a commit to a PR, my workflow only runs on pull_request and does not run on pull_request_target. Shouldn’t the workflow run on either of those events? Does pull_request_target already need to be on the default branch in order to run the workflow when a pull request is made?

on:
  pull_request_target:
    types: [opened, synchronize]