AI Generative Fill is grayed out in Photoshop 25.1

I upgraded to Photoshop v. 25.1 and now the Generative Fill dialog box is grayed out -- both in the contextual task bar and in the edit menu.  I have reset the preferences, and have uninstalled and reinstalled the app.  But it is always grayed out.  It worked in the Beta version for me. 
Have I overlooked something in setup?