Weird Light mass importance volume problem, help appreciated.

So im creating an archvis demo room and every time i try to use weird light mass importance volume it doesn’t work properly, the room is completely dark with no assisted light unless im just doing it wrong but here are some pictures, any help is appreciated.

Here is after building when adding the importance volume

No assisted lighting

This is during building the light
During lighting.jpg

This is the size of my light mass
Volume box around the house.png

This is weird because every time i move the back wall just a tiny bit, the lighting is suddenly fixed. is there some kind of light blocking going on?


any explanation or help is much appreciated.