This feature gets stuck consistently when the editor can not find an item to paste the element design onto. There needs to be an option to cancel out of this so the mouse pointer is not stuck in this mode. At the moment the only fix is having to refresh the browser and start over.
Thank you for raising this issue with us.
I will make sure to forward it to Product Team.
Can you please provide an example? (e.g. trying to copy form design)