Two things:

1) Better look at that display again, I have never heard of a 32 "channel" GPS. Besides, there are only 29 or 30 active GPS birds anyway, and you can't see all of them at once! I question what you are really seeing in the display, you surely are NOT tracking 30 birds at the same time. Now, it MAY be that it's telling you that is HAS seen all 30 birds, maybe that is what it is telling you. If so, fine. But my Lowrance has a screen that tells me what birds it CURRENTLY sees. Which display are you looking at?

2) There is some glass that is treated in a way that it becomes RF proof, we have seen this in the newer school buildings. The materials used are there for energy efficiency and UV protection - it's effect on RF (radio frequency) energy is an unintended side-effect.

Additionally, in the past two years, we here (at a small Motorola radio shop) have had two instances where aftermarket glass treatments (tinting) were actually causing the officer's radar to not work properly - the glass had become RF proof! So you see, there IS some possibility that the glass has been treated in such a way to make it RF proof, but I'd guess that this is not the case unless this glass is really tinted dark. Is it?