If the stream is a Heal/Light Blue type, I think it Miracles if it hits an ally or an enemy along the path. It'll restore HP to allies, and apply some Purify effect to enemies.
If it is any other color, it needs to hit an enemy along the path.

Damage chains only work if there are enemies to damage.
it is best to lead off with a red x 1 blue x2 and green x2 with the last red inside the circle but dead ended.

another possibility is that you were relying on pathing that changes as the miracles progress.

also, buy single use change-ups at the shop and take the quiz.
when asked what your wish would be... select triple purification xp.

fyi There were enemies to damage. I’m aware attack miracles can’t trigger without enemies alive and inside the chain. I always leave the zombie and 2 bats alone at the far end of the stage. I usually have all the portals feeding into and framing every edge of the stage minus the exits. I also make double sure the pathing can’t deviate either by placing an ally unit or change up at every potential turn.

I’ve done multiple runs since then and the problem seems to occur if I purify a portal that spawns at the edge of the stage and becomes part of the frame. Sometimes the chain works as normal. Sometimes it just doesn’t. The miracle occurs but the chain doesn’t happen after it.

And yes I do do the survey. Thanks for the advice.

i need an answer to this as well. Like we know how to do mass purification with all links, but why is the portal triggering is like only working 60% of the time. All thread i read about this are always useless answers of people that dont understand the situation. Yes we know how to connect and what color do, but dang in the last like 100+ mass purification i did i still dont know why it only trigger sometimes. In the end it feels like a bug.

The 2 primary reasons for miracles failing to trigger is that they need a valid target at the point the miracle should fire ( accidentally killing the last enemy inside the loop with the chain or prior miracles ) and that the order the game checks for "next trigger" etc isn't explained to the player at all (it's usually based on proximity to a specific map edge point ).