This has probably been going on for about a week or two now. I've tried it in both Firefox and Chrome and can confirm that the issue runs across them both.
I have the same issue. I tried to add Bioshock to my "queue" I have for myself and then bump it to my #1 in the list. When I save it disappears, and my list starts at #2...I also tried adding other games and they disappear when I save... I can continually re-add games but they always disappear.