I started a new game, and in the first duel I played one Forest and then tried to play Traproot Kami. As you can see, it went directly into the graveyard. My best guess is it died because its toughness was zero. However, I clearly have a Forest, so the toughness should be 1. It's possible some other bug caused it to instantly die, though. I'll update this thread if I find out additional information that may be useful.