Why is the "practice against computer" greyed out in my analysis window?

See topic. I set up an end-game position of King & Pawn vs. King & Queen. The position loads into the analysis view fine; I can make moves on the board and get the "gave review" evaluations, but the "practice vs. computer" button is greyed out. Why? 

I think you should post the fen or pgn of the position so others can try.

Good idea! Here's the FEN: 4K3/4P3/8/8/8/8/8/q3k3 b - - 0 1

Interesting, it's different now. I *can* click the "practice vs. computer" button, but if I do it won't let me make a move. It thinks it's White's turn, even though I selected "black to move."

Or maybe the computer just isn't moving? If I try to make a move for white it pre-moves. If I "switch sides" then I can make moves for black.

It's very confusing!