I solved the problem. It had to do with the main floor wall not quite aligning with the basement wall. That happened because I had to make adjustments after the floor was built in HD, once I realized our real architect had gotten some key dimensions in the kitchen wrong on our blueprints, that I had assumed were correct. They were correct for the first two phases of our renovations over the last 10 years. Anyway, I moved the basement wall into alignment using the display reference floor feature, and suddenly I can see through windows again.