So in my mod I've recently put some smoke spray-jets FX so add to a visual effect. It toggles between enabled and disabled depending if the player is in the trigger zone. However I noticed that when leaving the cell and then re-entering causes the smoke FX to become more and more transparent to the point where its hardly noticeable?

Am I doing something wrong or is there a way to fix this?

It will look perfect the very first time, but then after that it slowly fades away upon re-entering the cell.