Basically the game isnt recognizing its a window. It happens with open door frames or regular doors too. The doors are functional but in game the windows look like walls with a window frame like...
Ideas
Just to add more info again on my experience of this as I previously reported it on AHQ with images a long time ago. It doesn't matter if I use MOO, I've had it long before I ever used it (for a long time I mistakenly thought MOO disabled console achievements I only started using it with Modern Luxe). I've had it on Xbox One, Series S and now on Series X with all content installed. It doesn't matter what tile placement I use and affects doors, archways and windows while in build mode. I also had it on console with Sims 3 just out of interest.
For me it occurs after I've been working on a build for a while, it's not immediate. The longer I build, the more likely it is that windows/doors start to be affected. I've been testing it on a large build I've been working on for about 3 weeks now. I'm only using doors and archways to see if it still happens. There's no windows, it's just glass walls. The doors are still disappearing and even if I just go into build mode for a minute to do something, I have to check all my doors and archways before I go back into live mode because I'm left with just the frame and solid wall and have to click the frame to get it back.
