lichess.org/forum/lichess-feedback/bug-missing-queen#1lichess.org/forum/lichess-feedback/problem-two-black-bishops-missing-not-visible#1From time to time I experienced the same, recently when I switched the board color on the iPad app some pieces were missing on the desktop (spurious correlation?) Even so in the captcha, I had to play Qh7# without a bishop on say d3, it was an educated guess