I think it only shows up if you have 1 thread left. So, if you go into a boss fight with 2 threads, and die twice, you won't have a chance at that vision appearing for that run.
I've killed myself twice at a boss during my arc 1 daily runs, and it eventually showed up. I didn't die, and I start with 4, so I had 2 at the time. I don't think you have to be at 1 thread, specifically, but I'd wager you have to be at less than your max.