I’m having exacly the same problem.
I bought the living world because i needed the masteries to get Tyria done. I’m now failing for 1 mastery and i can’t progress because of this silly bug.
I’ve attempted to jump over to the Mystery Cave in order to get my mastery. Also bugged, when using the fire on the wall it just won’t do a thing….
An Answer from Anet would be awesome….