With Nintex Workflow Cloud, there is a known incompatibility with Safari Intelligent Tracking Prevention (ITP) and the way Nintex does authentication in the User Management and Personal Access Token pages. The page will display, but will show no records.

The work around is to disable ITP in Safari, or use an alternative browser.

This is due to Safari's incompatibility with Auth0's "Silent Authentication" feature, which Nintex utilises.