I am also having this issue
Finish vs Computer as black

It depends on whose move it is when you click "finish versus computer". If the move is currently white's, you'll be white, if the move is currently black's you'll be black.

If you go back one move so it's your turn, press finish versus computer and then make the same move that might help you workaround.
Hi!
I love the option finish vs computer but I can't find the option of finishing as black? Even if I flip the board before/after I push the button Finish vs computer I always end up as white. Is it possible to finish as black?