UPDATE: Have done some more testing and the canvas image wiping is happening with all users now. I have figure it out. :silly:
It looks like there was an Auto-Action that I had set up, but not completed, with the trigger "OnAfterCreateNotification". I did not realize the Adjust user field values was by default on the "canvas" item when first creating an Auto-Action. (see image).
I actually don't recall what I was trying to accomplish
The reason I was seeing it all of a sudden (the Action has been published for some time) was because I only recently figured out how to enable Notifications (System Auto Actions had not been enabled).
So, in summary it's NOT a bug, but rather a perfect example of "With great power comes great responsibility". The power of Auto Actions were at play!