Talk:Challenges/@comment-70.35.255.218-20190411131250/@comment-185.231.10.191-20190420001405

You must open the chest within 10 minutes of starting the game. The whole game timer must be under 10 minutes and the timer on the chest should show a positive number. If it shows a negative number you're too late.

This is very easy to do in Prismatic Trials that start you on that map, so just look for one of those if you can't get to it in time.