Unable to search for users in pull request intermittently

Issue Summary

Unable to search for users in pull requests even though there are users with repository permissions

Steps to Reproduce

1. N/A

Reproduction steps will be added once we are able to reproduce this issue

Expected Results

Able to search for users with repository permissions in PR

Actual Results

There are no users found when using the user picker "No matching users found"

Workaround

Load the user in the Users Admin page, then search for the user again in the pull request

Add the user to a reviewer group