Was running the mission solo to complete act III. Get to the end, fall once. Get respawned on the left side, the platform to lower the boss shield is on the right. Trapped near the portal, wait for minotaur to appear, open portal, reset mechanic. No more minotaurs spawn, one spawns after a couple minutes behind laser wall, dies to a random explosion and drops the key where you can see on the attached photo. No way to get it. Softlocked. Idk maybe a way to reset fights like this without having to do the whole mission again? A despawn timer for this kind of items? Don't think I'm finishing the story if I have to run this mission again. At least I got two secret chests for the catalyst, which kinda makes this situation more annoying 'cause this was being a long run already. Anyway skill issue on my part for running graviton lance I guess.