Can't find open pull request when using pull_request_target

[mehalter]

I'm trying to set up this GitHub action to comment on PRs using the pull_request_target trigger so that it works appropriately with forked repository pull requests, but I am getting an error:

 Couldn't find an open pull request for branch with head at .

Has anyone successfully used this GitHub Action for commenting on pull requests made with forked repositories and the pull_request_target trigger?

[ahnl]

This GitHub action worked for me instead: https://github.com/marketplace/actions/comment-pull-request.