I have to same, its been amusing trying to outsmart this squirrel. Yesterday I tried a new obstacle. I took a stainless steel bowl and cut off the lip of the bowl so it would not have a place to grip. I left the edges jagged, expected it be to sharp for the squirrel to grab onto.
This video is the following morning at breakfast time, it only took the squirrel a couple minutes to find a work around.
Few the video in full screen for best viewing.