Multi-User picker custom field

[Deleted user]

Why am I not able to find and select users from my JIRA project to put into a multi-user picker custom field from a post function?  It works fine for a single-user picker custom field, but when I pull up the post function screen for a multi-user picker it appears like just a text box and not a type ahead auto populate field like the user picker does?  Please advise how I can properly select project users to be put in the multi-user picker field.

Thanks, Ed