Custom field User-Picker showing no users

[Steve Lanaghen]

Basic question - I'm trying to set up a user-picker in a custom field and no options show up.

The assignee field shows the list of users just fine.  My custom field shows no options.  I am an Administrator and don't have an overly customized project.    Global "Browse users and groups" is set to allow the groups jira-users and jira-developers.  Project level "Browse Projects" is set to allow the same groups.  There is no user filtering for the custom field.

I've looked at other articles but nothing mentioned seems out of place.  Suggestions?