Heroic Karazhan Final Boss Game Freeze

When playing against the final boss in the Karazhan solo adventure titled “Free Medivh!”, the game freezes as soon as the cards are appearing for the mulligan. It’s obvious that the game isn’t actually “frozen” because the board animations are still going in the background. The problem is that I can’t select which cards to replace for the mulligan because they are still in my deck, but if I push the blue button to “confirm” my card choice, the game still doesn’t continue to progress to turn one. If I restart the game, I can sometimes play through from turn one, but I usually lose because I couldn’t properly mulligan. This forces me to go through this brutal process of the game freezing again if I want another go, which is really frustrating. I’ve seen other forum posts about this exact issue, but I often see no solution or a response from a Blizzard employee saying that it’s a PC issue, although it clearly isn’t. Does anyone have a solution? I really want my card back but this boss makes it almost not worth it despite beating every other boss :frowning: