VFB Source Composite vs LightMix

[ryan_companies]

Can anybody explain to me why there might be a significant difference in lighting/brightness between images when switching image source from rgb to lightmix to composite?
I currently have lightmix and back to beauty REs enabled, in the VFB RGB and lightmix are identical but composite is quite a bit brighter. These are interior shots and the difference seems to be mostly affecting the exterior/environment seen through windows, but it is affecting maybe the GI inside as well. Exterior lighting setup is an a domelight with an overcast hdri, and a vray sun.
Its hard to tell from these images, but just an example. The difference is much more pronounced in other renders.

Thanks.

[dimitar_panayotov]

You might have Affect All channels selected in the V-Ray materials, which could produce some differences.
It's described at the bottom of this page: https://docs.chaos.com/display/VMAX/VRayBackToBeauty
Sending a scene to us would give a better confirmation. You could do that from here.