This isn't a bug. It's just something they didn't explain very well. When you go into your inventory, you get the option to highlight a spe item type (armor, weapon, consumable, other, etc) by clicking on the appropriate icon. However, if you click, say, the weapons icon, any weapons in your inventory will be highlighted and everything else in your inventory will be darkened.... to the point where you can't see that they're there.
You've got one of the categories clicked. Unclick it. And everything will go back to being highlighted.
I noticed this feature, but it was the case also with the filters removed. It seems to have been corrected in the 1.0.3 patch.