something kind of along these lines: My bank had 2 mandrake in it already and it also had 125 items....When I tried to place more mandrake into the same container (and make my 2 mandrake turn into more) it said my bank was too full... However if I took 1 item out making my bank count 124, then I could place the mandrake into the container and it would stack like its supposed to, and I'd still have 124 items and could no put one more item in.
Actually, I think what you describe with the mandrake root has always been that way. What I'm getting at is that my 3 bod books are only supposed to count as 1 item each but were counting as 5, 10 and 33 items.
my issue had 0 to do with BOD books. If I have 125 items in my bank, one of those 125 being a XYZ stackable object, I can't stack anymore on to that object unless I get back bank item count to 124, then I can stack them, then add in my 125th item....
That also is known, but i'm not sure off if the check for stacking happens before the item count check of the bank. Most likely to insert another stack able item into your bank, you need room in case the stack cannot contain the overflow into a new item. The base item handler would not return all the way to the drag drop action, indicating a success or failure of the drop by the time it determined that a stack could not contain the item dropped. (This is a similar issue we are addressing for potions being created in the container where the bottles exist) I'll add it to the research list.
Not sure if this is a bug or not, but thought you might want to see it. EDIT: I think my client was out of sync.