Challenge completed without reward

[Wildfire2099]

That's happened to me 3 times.... the games gives you a bit (a second or two) after the clock expires before it brings you back to the regular areas. I think what happens is if the last hit happens after the clock goes to 0.00 but before you leave, it gives you the check mark, and the rewards, but not the completion bonus.

If you go do it again, and finish, you'll get the completion bonus.