I wanted to write you should always make sure that the transparency value of your material is set to a value of 70 or greater. Below 70 even glass is non-transparent. Of course the default of glass is set to a value of 70 or greater so it works correctly.
So this is what I wanted to write.
However, I just noticed that this transparency thing changed. I don't know if it changed in AC 9 or earlier.
Now if you have the transparency value set to 30 or less, the material is non-transparent, 31 or higher make it transparent.
I see that 30 + 70 = 100, so this transparency threshold might be calculated from the other direction (from 0, not 100).
I attach a screen shot so it is more understandable.
Sorry, it is a HUN copy of AC, but it is set to Internal Engine, and the arrow points to the Transparency value of the Dialog.
The Window on the left has a transparency value of 30, the one on the right has a value of 31.
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