how to add users to the drop down list for assignee

[Peter Bengov]

The users there can be any of the users you have connected to JIRA. 

But the actual users that will show have to be part of a group called Assignable User in you project's permission scheme. 

[Nic Brough -Adaptavist-]

Not necessarily a group though. The user must have "assignable user" in the project permission scheme, but you can grant that to groups, users, roles, dynamic roles (assignee) or even custom fields. I'd recommend a role, it's the most flexable option.

[Paula Silveira]

Hi Dan,

Please check on Projects Permission / Roles if the user is assignable and also check on Global Permissions if the user has Browse Users permissions.

If no user is listed, please also check on Global Permissions if you have Browse Users permissions.

Thanks and regards,
Paula Silveira