Hi,
Have you tired turning the TVs off at the Mains for 10 minutes? After powering the tv, power or restart pi.
Also have you tried changing the Input away from pi, then back. Does cec work then?
I’m assuming you have upgraded from the April release, is this correct? Also are you running the latest may release, 2017.05-2?
If all else fails logs will help.
Thanks Tom.