Unexpected results can occur on upgrade bids. We were notified of an upgrade acceptance yesterday...one of 7 that I placed for the Encore 4/16-5/1 sailing. I did not expect to be awarded any of them as my bids were only 60ish percent of maximum. Less in a couple of cases.
It was for a Forward Facing Penthouse, upgrading from a Club Balcony. I don't really get it, but I am certainly delighted (although not nearly as much so as my wife. 🙂)