Hi,
I successfully installed High Sierra 10.13.6 on a HP z620 after a bit of tinkering.
It has an Intel Xeon E5-2687w (without integrated GPU), the graphics card is a nVidia GT 710.
Now the strange thing: Airplay (to Apple TV 3) works flawlessly when playing videos from Safari (e.g. on YouTube) or if I select Apple TV in iTunes.
Mirroring however is not possible, the Airplay logo never shows up in the menu bar. If I select Apple TV as system audio output, there is some space created in the menu bar which instantly disappears ("flashing"). But still, the logo never shows.
Has anyone ever experienced a similar issue?
Any help appreciated!