Post-İnstance Mobs Can't be Ignited more than once

I am playing a cast on minion death with raging spirit and fireflower solar amulet. Mobs born after map already created like trials, breaches etc. aren't triggering minion death and my build is almost fully uneffective in these situations. I heard it is because of these mobs ignited only once and other minions just chilling near them.