It seems that whatever method I use to try and remove an item from only my watchlist, the item will be removed from all custom lists too. And there seems to be no way of adding an item to a custom list without first adding it to your watchlist. I consider the whole point of having custom lists is that you don't need to clutter up your watchlist with items that you may only consider purchasing once in a blue moon. This used to be how I used custom lists but this functionality has now been removed. I'm hoping it might make a return at some point.
