Do you mean when you click on the button, it doesn't open the Adobe Stock items in the EGP window? Or is it grayed out?
First question ... check your CC desktop app to make sure you're online with the Adobe CC cloud. Do something like use the menus to tell it to sync and see if it's connected.
It is Grayed out, Neil.
And I tried synch Settings. Nothing happened. My mail account was only synched. The Adobe stock icon remains Grey.