Update Exponential Height fog density from trigger box through timeline

So Ive got a trigger box in world that i walk over that when hit changes the density of the fog in level.
The problem im getting with this is that, though it does it over the time specified, it doesnt update in game until its finished, aka 0 fog until timeline is finished. It also doesnt update until the player moves once it reaches the desired value. Ive tested this with volumetric fog and it works fine, just not exponential height fog which is what i want to use

Not sure if its a render issue or just not able to do with exponential height fog? but any help would be greatly appreciated