Schwa raised it as an issue here http://bookclubs.barnesandnoble.com/t5/NOOK-Issue-Reporting/idb-p/newNOOIssueReporting - third item down - and if you give it Kudos it goes up the ranking to be fixed, apparently.
I'm so impressed you can even see your wishlist. I haven't seen mine for about a year. I think it works when I go into a store, but nowhere else. I used to be able to get to it if I cleared my search history and recently viewed list, but that hasn't worked for a long time.
Ack! Something similar just happened to me.
Previously, if I purchased a book that was on the wish list, it would remain on the list, but if I selected the item I could go to the display page for that item and select the "heart-minus" icon, which would remove it from the wish list.
Not sure when that method quit working, but apparently it has. Purchased a book about 2 weeks ago, and noticed it still on the wish list. But when I go to the item description, there's NO wishlist icon, minus-ed or otherwise.
Without serious diligence, this makes the wish list pretty much useless. Eventually it's going to fill up with purchased items, and there will be no room for "wish" items.
Is B&N hellbent on killing their own business, or what?