White squares using exponential fog

Hello everyone,
I’m setting fog in an interior area, but if I move the camera too fast or I change of room it appears a white square for a millisecond.

I took some pics in the exact frame when thhe white square appears

, in this room it is supposed to appear plenty of assets and walls… but instead, for a milisecond there is nothing…

No clue what it is or how to fix it… any idea?