I can not be specific with your design, because I don't have it, but I can help you with some general hints on how I would solve such a case.
1a) First of all I would try to plow all the traces that are not connected by hand until you are out of the rule area. In this way you could check if the rule area is set correctly.
1b) I would also check with iCES if the roules are correct in the rule area.
2) I would try to fan out the chip only and check if you can do a full fanout. If it is sucessfull you can add this as one of the initial step into the autorouter steps.
3) if everything else fails try to conntact Mentor support.
Hope this helps you.