My Tainted Pact + self-poison build randomly turns itself off

I am running a Tainted Pact + self-poison build, and it's dying when it shouldn't be. Wait. Don't go. Hear me out.

I have the flask enchant for leech on hit and I have Forbidden Rite on Cast While Channelling. This ignores cast speed slows and cooldown recovery rate. It will trigger every 0.3s so long as I am channeling. This is very reliable.

There are a few mechanics that I'm not certain about. Does flask effect apply to the leech when hit? Does the life loss from Petrified Blood reduce the "hit" for the purposes of leech? I believe they should apply in my favour, but it doesn't matter, let's calculate it for the worst case.

With 75% chaos res, I take 6% of HP as hit (petrified blood), and so leech back 0.9% of max HP, which will take 0.45s to deplete. Since the leech will trigger every 0.3s, the only case where I would not be leeching is if I am not channeling.

I am definitely channeling.

So, something is happening that is causing the leech to switch off, and subsequently, my build's life.

I've checked:
- I have mana for Forbidden Rite to trigger.
- I'm not being hit by anything that would cause the Forbidden Rite damage to kill me. More evidence of this: looking at the replay, I am not dying as a Forbidden Rite projectile is being created, nor is my mana level changing as I'm dying. I always die with full Energy Shield.
- I am playing on Lockstep networking mode, so I'm not actually somewhere else.
- I even anointed the notable to increase maximum leech per leech by 20% to make it more certain that the leech is still going.

I think...
- It doesn't seem to happen around any particular enemy type.
- This seems to happen in clusters. Like, it'll happen a few times in a 10 minute period, then not at all for the next 30 minutes. Maybe a server tick rate issue?
- since Patch 3.21.2, when I watch the replays back from OBS, the life bar only updates every second frame, now, instead of every frame. I don't know if that's possibly related?

Evidence: https://youtu.be/SF5C617nQjU