Display names are not showing properly on Confluence

Issue Summary

Display names and profile pictures are not showing properly on Confluence.

The users' names are showing as "User XXXXX" instead of their display names at multiple places.

Steps to Reproduce

We reproduced the issue on:

1. Home dashboard (Feed section on the home page)
   
2. Space Settings (the Administrators list)
   
3. Space Permissions (the Individual Users section)
   
4. Pages (updated and last modified)
   
5. Mentions
   

Expected Results

The user name should be displayed as their public name.

Actual Results

The user name is showing as "User XXXXX" as their public name.

Workaround

Sometimes refreshing the page works, sometimes it doesn't.