Can this problem be verfied, or is it my mistake?

It's not your mistake, it's mine. Said an other way it's a bug.
I fixed it in the beta version of the upcoming version 3.2 (it requires you install Java).
This modification in the photo rendering might change how transparent models are rendered in existing homes, but from the numerous tests I made, I'm confident the colors and the shadow of transparent models are much more accurate than in version 3.0 and 3.1.