Very frustrating end of game.

I can certiffy that I tried my best with every available tweak and was still not able to clear the level.

The screen faded out every time I was in the middle of the incantation. I had double timer checked, maxed out movement speed (I blazed through the level in like 15 seconds, not having to worry about obstacles as they were too slow to impact me). Yet this still did not prevent the screen from fading during incantation at the portal.

It feels like there is a sequence of things you need to do at the portal (puzzle), and I did not do the sequence right so the game killed me. But as far as I know there is no puzzle, you just run to the pillar and apply charm at it.

I had no other option than to enable "dev continue" in the cheat section of the patch, enabling me to continue after dying. This way when the screen faded and informed me I died I simply hit dev continue and casually walked into the portal, which took another 3 seconds to open by the way, so there is no way I would be able to somehow shave off another 3 seconds of the (already near-perfect) run.

So now I'm confused. Is it the cpu timer/fps issue, or is it some other trigger that kills me? How do I check if the v-sync option is actually working and limiting my fps to 60? I did not see a checkbox for it anywhere.