Hearthstone on Twitter: "We're currently aware of an issue some players are having when entering The Puzzle Lab and are looking into it. We'll be providing updates as soon as we're able
Hearthstone: The Boomsday Project Explodes With Its Puzzle Lab Launch
Puzzle Lab - Hearthstone Wiki
Dr. Boom Puzzle Lab Solutions Guide - Dr. Boom Puzzles List, Answers, & Tips - Hearthstone Top Decks