By default, the Playlist button will only search for unassigned tickets (Assignee is blank). If you need to pull tickets that are already assigned to another agent, you can now include assigned tickets when searching for tickets using the Playlist button.
This is useful if your views, for example, have tickets that are assigned to out of office agents. Your workflow may require you to preserve the Assignee unless it's assigned to another agent.
To include already assigned tickets, simply check "Include assigned" when creating Playlist rules.