Yeah, the bag that the spear and note was in is now bugged for me, too…
…also I can’t seem to post from anything but my Classic characters either. That’s interesting…
Edit: To make matters worse, I think the bugged item is in one of the “locked” slots…and I don’t know why they’re locked. I have an authenticator too, and even if I didn’t…wrong bag? hah
Edit 2: I managed to empty the ‘invisible’ slots out into the bank so I saved those items. I then went out to Northrend, and now I notice my bag is back, but empty except for one item, Bobby Carlisle’s Thinking Cap Notes. I noticed when I accepted his quest, it just marked it as completed in my chat and nothing else happened, and I didn’t see the notes in my bag. They seem to be there now, though…
…maybe the REAL mystery is…how to fix your bags?
Edit 3: After reading through the other post Here, it seems that it was something to do with Bobby Carlisle. Apparently his quest isn’t supposed to be for today, and having the item made the game unhappy? Not sure…but I’ve since deleted the item, completed the mystery for today, deleted all remaining items, and my bags are back to normal.
Edit 4: It seems maaaaybe Bobby is no longer giving the quest, since a friend of mine just looked and he didn’t have one, so, maybe the caught it and stopped it. Hopefully it won’t bug anyone else’s bags now!