Yes, umpire's call if ARC inconclusive.
But, as I explained in the game day thread, there was no basis for the goal umpire to call it a behind as there was no evidence the ball touched the post, and the ARC failed. The goal umpire should have, in the absence of evidence the ball hit the post, called a goal. Then the goal umpire should have stated he was not sure and called for a review (I think he did this and it was correct to do so). Then the ARC should have resolved the situation, but it failed.
DS