Ranked Game Loss (when I haven't lost)

I just qualified for a ranked series (in S5, attempting moving to S4). I won a game, and got a message that I advanced to my promos.

I played a second game and won. I noticed in the game recap screen after the 2nd game that it showed 1 win and 1 loss.

To make sure I hadn't lost my mind, I checked my ranked history. Indeed, I have won the last 3 ranked games.

This is a stupid bug.