what are you calling an emitter?
Deco Mist (FairyTail), Waterfall (Maritine Riffle) and Torches (Trainingcamp) are particle emitters just like the smoke from chimneys.
I've noticed different things can have negative effects on the particle emitters.
1) placing them too close to each other can stop the function of one or both.
2) placing regular items near emitters can sometimes stop the function.
3) too many emitters.
I've always considered it to be a limitation of the game coding. What do you think? Have you experienced this?