How do I troubleshoot Airplay devices not showing up? I use the Airplay feature of my laptop at work and at home.

With no change that I'm aware of, my laptop can no longer see Airplay devices (Apple TVs) to connect to at work. 

Other people's at work have no problem.

I have no problem at home.

What could cause Airplay to suddenly not work, only for me, and only at one location?
Turning Bluetooth on has fixed this. 

Having Bluetooth on at home is never required. Apparently there is a Bluetooth discovery feature in AppleTV (I suspect they have recently been configured differently at work).