I confirm this bug (couldn’t have posted earlier — caught a random block on the forum, sorry).
Tested it right on the first day of the new cycle, even crafted Ysera the Dreamer — the puzzle doesn’t start anymore. Replacing her with the new Core Ysera doesn’t work either (come to think of it, haven’t tested Legacy Ysera, and I even have the original card, but it doesn’t make much sense).
The fix is yet to be seen, apparently.
The puzzle is fun, I wouldn’t mind replaying it even if it costs some cards, but sadly, I haven’t been able to access it since the rotation.