Not sure whether it's paperpile's problem or PDF expert's one. I star some papers, I see them in starred folder, I annotate them using PDF expert, but then when I save them, they are still in starred folder, but pdf expert does not see them! It tellms me "empty folder". They are physically present in google drive/paperpile/starred, pdf expert sees this paper in a regular folder starting with a capital letter, but not in starred folder.
Any ideas what the problem is?