Cast on minion death not working in certain situations

I play on Geforce Now, Sorceress.

Build cycle works like this:
Fireball is fired, raging spirits are spawned. Spirits die from applying ignite due to the fireflower amulet or minion instability. Then Cast on minion death either spawns an icewall as target to fire the next one in or a comet. This can become quite the flurry that simply ends when my mana is completely devastated.


This mechanic works well so far for:

- Maps till t14
- bosses of all types, rares of all types


However, in the following instances it stops working:

- Breach
- Delirium mirror/Fog
- Survival 90s trials in Trials of Sekhema


I don't know if I am missing some kind of super resistance game mechanic here. But when I apply my fireball, minions spawn. At best when one dies, one or two frost walls go up. And that's it.
Now, even if they do not die from ignite, they should die fast. On all maps, this usually ends in a few comets falling when they are left after a fight.

But there, nothing. At best an icewall here and there, almost zero comets. But it should spawn comets, albeit much more slowly, even if the mechanic does not work due to resistances. That is because the minions die by themselves from instability and on a normal map, comets then fall. But the moment I either open a breach, delirium mirror or start one of these trials, no chance. In Sekhema, a chalice trial will spawn all the comets, a survival trial will get me up to exactly zero.


Is this a bug or a feature that breaks my build?