asignee list not showing all users

[Udo Brand]

Check your permission scheme, look who has the assignable user permission.

[Anil Gupta]

I have given the user the administrator role. Still I don’t see him in the assignee list when I want to assign a task to the other user after adding a  comment or changing the task status.

[Nic Brough -Adaptavist-]

Admin does not mean "can do everything", it means "can do admin tasks" (admin can do everything is a dreadful approach and Atlassian don't do it). You need to add them to a role that has the assignable user permission, as Udo says.

[HP]

might be the permission issue? (because user will not in the list if he/she do not have permission to work on ticket.