I was doing a big sort this last week. Many of my colorless cards did not seem to be showing up correctly.

My sort filters are:
Type - is none of - land
price > 5
number of colors = 0

I noticed 5 cards in my collection missing from the results:
Buster Sword
The Walls of Ba Sing Se
Emrakul, the World Anew
White Lotus Tile
Tezzeret, Cruel Captain

All those cards are in my collection, but they just dont show up in the search.
If I reduce the sort to just search for cards with no color, they are also missing, so I think that is the field that seems to be messed up. Some of them are "special" treatments...tezzeret and emrakul, but the others are all the base version.