This sounds like it could be linked to the build present on your M6. I've never had luck with Frodo, Gotham was OK at times, Helix I've not yet tested (no Apple hardware of my own, I have to grab passing iPads/iPhones!)
Head to the System Info entry under the System menu in XBMC.
Something like that. XBMC 13.2 is the part we're interested in.
If it is 12.something (so Frodo or Flump), I'd recommend installing SPMC from their website. Select the
Gotham non-launcher APK and contact us at
[email protected] for a link to the wizard. See
https://droidbox.co.uk/blog/how-to-retrieve-your-wizard-username-and-password/ for grabbing the username/password for the wizard.
If it is 13.something (so Gotham) then double check System>Services>Airplay is OK
If Gotham doesn't help, we could try a Kodi build.
Please excuse the delay with this reply, I'm attempting to get through all unreplied threads now.