I don't think the price is jumping though it could be. The unlocked seats are pricier than the locked seats. The code unlocks the locked seats if you can solve the riddle.
There seems to be an issue with the code a) not working on mobile for some reason, and b) not actually unlocking for a few minutes after the window opens (the “no tickets available” message that showed up the last couple of days).
You can bypass the code window by clicking OK and perusing a small set of tix that are available at elevated prices, or wait it out and the code eventually starts working.