I experienced this in a game last night. Opponent played Thought-String Analyst on turn 2 and exiled a card from the top of my deck, which turned out to be Fable of the Mirror-Breaker which he played on turn 3. He did not lose 3 life upon exiling the card as he was supposed to. He did not have any lands or other permanents in play that would have prevented the damage.
I experienced this in a game last night. Opponent played Thought-String Analyst on turn 2 and exiled a card from the top of my deck, which turned out to be Fable of the Mirror-Breaker which he played on turn 3. He did not lose 3 life upon exiling the card as he was supposed to. He did not have any lands or other permanents in play that would have prevented the damage.