I was just using up my Shadowkin faction war keys. I did stage 14 with 1 star, and 15 with 1 star. I accidently hit replay instead of edit team, as I wanted to try and 3 star it with a different combo. When it loaded up the next battle, I ended it instead of fighting through the battle. The defeat screen came up, and I went from 10 keys down to 2 (double raid was clicked on, so 4x2 keys used). So from the 18 starting out, 4 used on 14. 4 more on 15 puts me at 10. The defeat / end early on 15 (with double raid on) put me at 2.

I'm guessing a bug in relation to the new content drop. Any help would be cool.