Here's a bug I just came across.
I imported a picture and set a drop shadow to it... I eventually save my document and now when I open it I still see the shadow and the picture BUT the picture is said to have no drop shadow applied. And now, there is no way to edit or remove the drop shadow in qiestion.
In fact, we even deleted EVERYTHING on that page and still the drop shadow remains.
Thumbnail dragging into a fresh document re-established the drop sahdow preferences.
Hop this helps!