Invisible Volatiles?

After entering a 'Coves' map during a Harbinger encounter I heard a sound. It was probably a volatile but I wasnt 100% sure. Anyway I was looking for it. Shortly after all the mobs in the vicinity had been killed and there was no gfx spam to hide a volatile ball. In this situation suddenly (without me seeing any volatile even though I was looking for it and the situation made it "impossible" to miss the volatile gfx) something suddenly took ~50% of my health.
The volatile (if it was one) most likely was killed off screen by one of my poison Siege Ballistas.
This is not the first instance of something like this happening. There have been several similar incidents.

In case it matters: I am currently playing with lockstep without preloading and have issues with "stutter lag" - mostly after entering an area. Also in certain lab trap gauntlets - esp one of the gold key ones. Performance was better for 3.0 - I had to switch to 'dynamic resolution' because otherwise PoE would oeverheat my GPU. Even though gfx was smooth somehow the Harbinger (and Kitava) gfx implementation is so that it causes GPU overheat for me. It is possible that the stuttering is due to bad implementation of dyanamic resolution adaption algorithm. From my POV it is also possible that the "stutter lag" is due to GGG not spending enough server money for smooth gameplay. Did not investigate the cause so far.

There are various threads on the forum which may be related. Like:
https://www.pathofexile.com/forum/view-thread/1977214
https://www.pathofexile.com/forum/view-thread/1983148

Also: I have read claims that the asset loading can lead to this. Obviously it needs to be implemented in such a manner that volatile gfx is loaded reliably and sufficiently early.

Edit: There was no stutter lag at the time of the health loss. I have ping of 30..50 usually but it can spike if there is stutter lag.

Edit: 'many' -> 'several'

Probably one more instance of 'invisible volatile' but not 100% sure.

--

Some update on the stutter lag: Just tested various configurations and most of the stutter lag is caused by Dx11. With and without dynamic resolution. So dynamic resolution adaption algorithm is probably (from my POV) not cause of stutter lag.
And I didnt get GPU overheat with Dx9ex so far - so the Gfx programming is probably improved now. Will continue to use Dx9ex.

Just had this happen again. Odds of it being visible and me missing it <<1%. There was nothing else notable on the screen which could have made me miss it. Especially after hearing the escape sound.

Situation was: Fighting some mobs in Elder infested Shaped Ashen Woods. I hear the escape sound of the volatile but I did not see any volatile ball nor had I noticed a volatile monster. (So it is possible the volatile monster was off screen at the time.) So I continue playing expecting a volatile ball to catch up to me - or me getting out of range. What instead happened was me loosing some life/mana and hearing the volatile explosion sound. This was when I was idling a bit for a moment. Which is all consistent with getting hit by a volatile. Except that there was no gfx for it.

This was the first volatile after starting up PoE. It may be a bug/misbehaviour with the asset loading code.

Video evidence of invisible volatile core: https://www.reddit.com/r/pathofexile/comments/8fi2tj/invisible_volatile_in_t16_almost_team_wipes/

Related link in there: https://www.reddit.com/r/pathofexile/comments/8cp5bk/this_streamer_using_a_very_interesting_pluginim/dxh5373/