Is it intentional that they stay unopenable, and you can continue to fight the bosses on non-standard floors spawned by the fortuneteller? I killed a Shackler on floor 12, and the task highlighted green, but the chests were still sealed and the boss was still there, and speaking to it repeated the battle.
Think I found the problem, thanks!
This is still happening.
Fixed (and actually tested this time!) for the next patch.