After completing the grave matters event, the chest with the reward did not appear. How to fix this problem?
Going back in time a full year. Grave Matters from 2.7 is not the same as Grave Matters in 3.0, there is no chest anymore.
Suggesting time travel as a solution is really, really irresponsible. It tends to create more problems than it solves.
Unless you’re a scriptwriter for Marvel Cinematic Universe, in which case it’s not irresponsible, only lazy.