Apollo, I thought we tracked down your particular issue a long time ago. If you can give me particulars, I can look into it again. If I remember correctly, for some reason the database had that you owned something but it wasn't tracked in your collection.
The problem I'm experiencing is that when I go to add games to my wishlist, the search will start displaying games I already own after a few pages, so it's very similar to the issue Dav1d has.