Hi Eric, I appreciate your time and suggestions to solve this issue.
I did exactly as you requested and could not even get airplay to display in the menu bar! That's for the new account. Got no joy at all.
Got into safe mode and it did exactly the same process (in my account), as if I had log in normally. Airplay is displaying the icon top menu bar on the right near wifi icon, I click on it and it continually displays searching for ATV the straight to "OFF." This is a continuous process.
Hope this gives you an idea. I also note my 4K ATV will not stream images from my iMac correctly. Music alone all good. I also noted that iTunes on my ATV displayed incorrect information about a track in my library, but when I searched the artist it was correct? I am suspecting a bug now. I am not computer savvy like some so bear with me if I have have missed something out that assists.
I applied the home sharing to the ATV which randomly says my library is not available but displays it correctly. I go back in and try again and it flicks off giving the same message. I timed the fall-overs and they vary in times no pattern at all?
Regards
Mitch