Whilst fighting the sovereign eye as the 2nd last step of this story quest, if you kill the eye before he resets to the middle after porting to the door to do his multiple mind stab like attacks, he wont register as being killed, thus you are stuck and have to exit and redo the whole story mode event again from the beginning.
This has happened several times and should be fairly easy to reproduce.
As you can see from the attached screenshot, the eye is dead and it registers the tick but the story doesn’t progress.
