Steps to reproduce

1. Login as Admin
2. Create a page and go to the object editor
3. Add a AppWithinMinutes.Groups then a AppWithinMinutes.Users field
4. Click on the new fields

Expected result

A suggestion appear for the two fields.

Actual result

The first field has suggestions but not the second one. (404 not found error: http://localhost:8080/xwiki/rest/wikis/xwiki/classes/undefined/properties/undefined/values?fp=&limit=10)

The suggestions appear of both fields after reloading the page.