Yeah what I was told from someone who was a producer of AMW was it wasn't really the ratings (which admittedly were not that great but better than what Lifetime previously had on Friday nights) but the cost of the Fox licensing fees that led to ultimate cancellation.
That is a big disadvantage to network ownership of television programs. Such ownership seems good in theory, but what's good in theory is not always good in practice. Policies on network ownership can vary. Some can be soft while others can be so stringent that, in the event that the network canceled the program, shopping it elsewhere can be easier said than done. That's why, in hindsight, it was a good thing that Unsolved Mysteries (AMW's competitor) was not a network-owned series. If it were, it would have been difficult, if not impossible, for another network to pick up the show after its cancellation by NBC in 1997.