AirDrop between Mid-2013 MacBook Air and iPhone 6S not working
I also suffered from the same problem, although wifi + bluetooth are in the on state in both devices, finder window was empty.

But when I tried to send a photo from my iphone to macbook, suddenly my iphone identified &amp; shown in finder.

My devices 


MacBook Pro 2012 Mid -El Capitan (10.11)
iPhone 5 - iOS 9.3.1