Simple Portals Bug in V-Ray Next.

[Algehov]

Hello!

So ever since we upgraded to Vray Next we've had an annoying problem in a lot of our scenes. We always comp our images with render elements, usually from subtracting them from the beauty render, do the tweaks and then adding them back on.
But since Vray Next our GI often have too much light compared to the beauty resulting in negative values when being subtracted.

We usually set up the node tree in Nuke like this:
https://i.imgur.com/YXaNfuc.jpg

So Lighting and GI is being subtracted, and you can grade the reflections individually (along with lighting/gi/diffuse if needed), then its all added back in the end.
Before we noticed what was going wrong, we just saw that some of our renders after lighting was subtracted, had issues with the reflections being very dark, and often blue saturated parts in it. Looking like this:
https://i.imgur.com/2yt9HZM.jpg

But the reflection and specular render elements looked fine.

If you rebuild the beauty render with all its render elements it will be lighter than the beauty render.
Beauty render: https://i.imgur.com/RhR4ANS.jpg

Built with AOVs: https://i.imgur.com/eviPIos.jpg

I've noticed this only happens when we're using Simple Portals in the scene. So whenever we have a physical sky plugged in, or a hdr plugged into GI instead of a dome (so we can use portals), this will be an issue in our scenes.
I know the new dome light has adaptive dome light as a setting, but we often want to add a portal in a hallway to get some extra sky light there, or increase the diffuse contribution of a portal etc. We dont have this control with the adaptive dome light.
This was never an issue before Vray Next.

I've set up the simple scene you see in the renders that has this issue, along with a nuke script where you can see whats going wrong. You can download it here:
https://www.dropbox.com/t/smDXZ8ZoVWF3X20R

Do we need to do something different to get this working again, or is this a bug on your side?

Thanks in advance,
Simon

[yolov]

It would be best if light portals are not used at all, since they are likely to break more things than just compositing, being a cheat in the render.
I did some tests with the scene and had the render time cut in half with no issues in the comp by disabling the lights that were portals, adding an adaptive dome with the sky texture in it (with the sun still in the scene) and turning on adaptive lights.

[Algehov]

Yep, I know about that. We will try to stick to that as much as possible with all new scenes.
The problem is all our older scenes have stopped working for when we need to do updates (but we can load them in vray 3 for now and stay away from newly created assets).
But you lose the ability to push in some extra sky light from a specific window, or even from a place that doesn't even have an window. You cant do that with an adaptive dome light, and portal was a great solution for it.

I also find it strange that his has been working with no problems before, but now its broken, and the solution is to leave it broken since there exist a different workflow that makes some stuff better and other stuff worse.
I don't understand how the GI render element can be lighter than the actual render. Some math doesn't add up here.

S