Maybe this is well known, but I didn't know it until yesterday.
DO NOT PLACE A BET USING YOUR FREE PLAY ON ANY OUTCOME THAT CAN TIE/BE CANCELLED. If it pushes, It will be graded a loss for Free Play purposes, rather than a push, where the Free Play is refunded into the free play account, like other places.
This is a horrible rule, but it's in their rules so I can't complain if I get bit by it. But I can warn others to not be as stupid as I was.