Can't see through windows after increasing thickness to 0.25"

SketchUp Pro
1

I’ve had trouble with Z fighting on the windows you can see in the animated GIF. So, I increased the thickness of the windows & frames to 0.25".
That created a new problem. Even though I decreased the opacity to 10%, I cannot see through the windows. How can I see through the windows and avoid Z fighting at the same time?

Peter
Can't see through windows
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Complete Left Hexagon.skp (247.3 KB)

2

The end wall is loose geometry. There is an extra face on the back side of the window.

And there is no cut out for the window in end wall.