Stuck at "This may take a few moments" Advanced Data Protection

Hello,

I just enabled Advanced Data Protection from my iMac. All seemed to go well, except it has been at this screen for about 30 minutes. I checked both my iPad and iPhone which say that ADP is enabled. So, is my iMac doing something?? I can't cancel it, nor log out or restart. My only option would be to hard power it off. Maybe I could disable it from a different device first, but don't know if the would be necessary. I'll give a bit longer. Thoughts?