I am unsure if I missed something but I played From De Other Side with Therazane in my end and that interaction was fine. Therazane deathrattle worked correctly but when I went to play Therazane the next turn, she immediately died. The deathrattle worked but as soon as she hit the board she died.
You probably played a randomly generated Shattershambler earlier in the game. It’s an elemental with Battlecry: Your next Deathrattle minion costs (1) less, but immediately dies when played.