Sorry, I’m not sure what you mean about the first answer? If you mean RevenX’s comment I don’t think I see anything about materials in his answer.
There are actually a few more windows on the opposite side, though you’re right in that they shouldn’t be flooding the room with light. It just seems like pitch black is a bit extreme when the outside is so radiant.
It really does seem like my sunlight hits a single surface, and then stops dead (except if I use that one material from the lightroom, I can’t explain why that seems to work fine. Other materials, including white ones, don’t reflect at all). If I build a room with plenty of windows, any shadows will still be pitch black. Surely that can’t be right?