How to have an incident auto-assign to someone if left unassigned

Hello Sysaid folks,

Currently we have an escalation rule that automatically assigns any status 'new' incidents to our level 1. The issue we are having is that any job that is unassigned and has a status OTHER than 'new' does not get auto assigned.

Creating an escalation rule that assigns all incidents with status 'active' and a blank assigned field, just assigns ALL active tasks to the level 1, even when they were already assigned.

So my question is:
How can I create an escalation rule (or similar) that automatically assigns any UNASSIGNED incidents to our level 1, after they have been sitting unassigned for 15 minutes, regardless of their status.

Cheers