Here is the solution/work around at least for me and my NON-ROOTED Samsung S7. This is what worked for me below. The key is to use the PC-based client/application to initially authenticate the device,
NOT the web application. After you do it once, it will work
unless and until you reboot your phone--remaining bug for AD to solve.
1. Sign out and close out of
any and all sessions (i.e. AirDroid Web, Local PC App, phone app, etc)
2. Restart your phone
3. Start AirDroid on your
PC -- NOT the web app.
4. Select your Device (on left), then select the Air Mirror Icon (bottom right)
5. Make sure USB Debugging is ON (Settings>>Developer Options) --
AFTER authorization, you can turn this back off and it works fine.
6. Plug in USB and follow the instructions to authorize
7. Exit your PC AirDroid application
8. Unplug the USB
9. Restart your the AirDroid Phone App (do not restart your phone)
10. Now log into the
WEB version of AirDroid (NOT the PC version)
11. Chose AirMirror and it will work
Notes: if you restart your phone, you will have to re-authorize the device using the PC Application again (unless you are rooted, I assume).
I also found that if I execute an AirMirror session while locally connected using the PC Application, it removes the authorization and you have to do the process all over again.
I'm sure AD will work out the bugs soon.