I was analyzing a game from my activity and tried to "Continue from here" from the resigned position to see if I could win it against Stockfish. Unfortunately, when I choose "Play with the machine", the pop-up dialog box is missing the buttons for Black-Random-White, so I can't actually choose a side and play. When I log out of my account, however, and then go to my activity and try the very same thing, I can play the position out against Stockfish.
This happens in Chrome 71.0.3578.98 (my usual browser) and in Microsoft Edge. Dell Inspiron Desktop. I've tried logging out of lichess and clearing the browser cache. No joy. [Edit: also happens on my chromebook.]
Link to problem screenshot: bit.ly/2AS2idF
Link to signed-out situation working correctly: bit.ly/2FM5knj
Link to game: lichess.org/k7HxMxGTPHlh