I was attempting to complete “Fastest in the Land” by doing 2 quests within 5 seconds of each other. Twice in a row a friend and I did Into the Nest, got Grim + Tome + Elites and grabbed the grim and tome simultaneously.
We continued with the level and the game crashed as I was overheading a Stormvermin. The second time it happened at the same general area and my friend commented that it was the last Elite needed for the 3rd quest.
I believe having 3 quests is causing the game to crash with the challenge already complete.
[Script Error]: scripts/settings/dlcs/lake/lake_achievements_settings.lua:61: attempt to perform arithmetic on upvalue ‘timing_time’ (a nil value)