I haven’t received a chest.
The gw2 discussion subforum has already threads that discuss issues with the karka chests. Please, check this one in order to see a discussion about what the other players got. For an official discussion about the solution with official ANet statements inside, check this one. There is also another one about the fairness of the karka chest rewards, here.
Please, feel free to contribute in any given thread.
We proceed to close this one. Thanks for your understanding.