Hi Ishikawa thanks for posting! I tested this on my end with shapes from our Standard and Flowchart shape libraries and saw the same behaviour so I have reported this to our development team as a bug. As a workaround I recommend copying and pasting the shape style from another shape which does not have shadows. To do this select a shape without shadows>right click> Copy Style. Then select the shape(s) for which you want to turn off shadows right click>Paste Style.

Ishikawa I created a Support ticket from your post so that we can notify you directly when this bug is fixed. If anyone else is experiencing the same issue please feel free to let us know on this post. I will update this thread when the issue is fixed so you can either follow this post or contact the support team directly using this form if you would like to be notified of any updates. 

Thank you again for bringing this to our attention and I apologize for the inconvenience this may cause. Let me know if you have any questions!

Hi Emma thank you for your prompt reply and the creation of a support ticket!
I understand the workaround.
If I find something that seems to be a bug I'll create a support ticket directly from now on.
Thank you!

@emma d I also have this issue. Your workaround works but looking forward to the fix.