Ahhh man this problem has been driving me nuts for about two weeks now. I did find a temporary, if annoying, solution though.
After reading someone's response that said when they went to the iStore their Airdop suddenly worked on the stores wifi I thought I would try while not connected to any wifi networks. This totally worked, but it's annoying because it means deleting your wifi network from your mac and from your phone and then sending the files and then re-entering your password on both devices to carry on with your life.
Like I said, really annoying.
This confirms that the problem lies somewhere in El Capitan though, and has something to do with wifi network settings or protocols. My Airdrop used to work fine before El Capitan when connected to any wifi network, but ironically it wouldn't work when I wasn't on a wifi network.
I knew the problem was lying with the Mac when I could see my iPhone with my iPad and vice versa, but the Mac couldn't see either of them.
I'm a huge fan of mac but I must say that since this problem has come about I've found myself feeling incredibly annoyed with Apple because not only does it not seem to be getting solved, but there is literally nothing that can be done to fix it on the users side.
As someone who use to use Airdrop as part of my day to day activities in order to share photographic or videographic previews with clients, it really inconveniences me. Yes I can email or iMessage the files, but that means wasting redundant space on my devices/email servers.
Hopefully they will fix this with the next upgrade, which might be in who knows how long.
fyi I tried the following in my journeys of frustration:
- logged in and out of icloud
- changed icloud passwords on all devices
- reset network settings (as best I could, seems like you can't completely reset it, I tried what a few sites told me and found that my wifi settings were still intact despite my best efforts)
- done all sorts of recommended rubbish in terminal that I found on a variety of threads, none of which made any difference
- deleted the bluetooth pref file
iPhone 5s: iOs 9.2.1
iPad Air: iOs 9.2.1
MBP Retina 15-inch, Mid 2014 - El Capitan 10.11.3