Default reviewers does not work on PRs created from forks

We've defined a set of default reviewers in our BitBucket Cloud repository.

However, it seems to have zero effect. Any time we create a PR from a fork, the list of reviewers is always empty and the list of default reviewers does not seem to get applied at all.

This is confusing and frustrating. The pull request is being created in the repository being merged into and not the fork. Why wouldn't default reviewers have an effect?

Adding to the issue I can't add default reviewers to my private fork unless I give access to the fork to all of the reviewers who already have access to the main repository. Effectively each user can only add themselves as a reviewer which is rather silly.

I can however add the users manually every time I create the pull request but the entire point of having default reviewers in the first place is to remove the need for doing this.