I've recently upgraded our MARS to 6.0.1 and IPS from 5.x to 6.x and after that I have one issue.
Now I can add a "virtual sensor" to the IPS 6.x device. I have the default vs0 virtual sensor, MARS discovers it with device "addition" and then MARS uses the "myIPS/vs0" as a device when displaying events. The problem is that now I receive "Inactive MARS reporting device" concerning the main sensor (not the vs0). I use this event as part of health-monitoring of my devices, but now I can't definitely say if my IPS is active or not.
What is the solution?
You can filter that particular 'reporting device' from the built-in unknown alerting device rule. You can use the not equal to (!=) operator.