This is part venting and information sharing.
My set up is very simple. I have a mac book pro, a mac mini, an Apple TV, a Samsung TV and an Onkyo AV receiver.
I have been able for several years to turn on the Apple TV, and go to an icon "Music". Listed in that screen was my mac book iTunes library and the mac mini library. The mac mini is connected to my network by ethernet cable as is the Apple TV. When I selected the mac mini library the library instantly loaded and I could find artist, album or playlist(s).
Yesterday the Apple TV (generation 3) automatically upgraded the os. When I went to music icon, the only selection was to turn off home sharing. I spent the next hour resetting my appleid, on all my computers and the Apple TV. But still could not get the libraries to display. So, I called Apple tech support using the mac mini apple care account.
I spent 2.5 hours with tech support trying to load the libraries. We did screen sharing on both computers. We shut down every device including the Apple Airpot router. We were able to launch each computer's screen to the Apple TV. But no iTunes library showed up?
He took a 30 minute break and called me back.
He had done some research and spoke with other techs. They informed him that the new version of the Apple TV os has a new icon "computers" at the bottom of the screen. This icon cannot be moved to the top of the Apple TV screen and the operation seems much slower than previously. I wonder if this is all part of the iTunes breakup?