Lightning flashes inside interior corridors

[Red04SWBF]

I had discovered another bug while fixing Kamino: Cloning Facility from SWBF2. It's about the lightning effect. When passing through a corridor inside a concrete MSH, the effect of the lightning is seen through the walls. This shouldn't happen since in Kamino SWBF1 (Tipoca City) this doesn't happen. I've tried to find out where the problem comes from but I haven't found anything to solve it.

Any idea / solution?