ARC should not be used. It's a feature, that was very poorly designed and implemented.
Hook all your sources to your A/V receiver, then run HDMI from your receiver to the TV. If you have some audio that's in your TV that you want back at the A/V receiver, then I would use optical audio out from the TV, if available, and run that into the A/V receiver.
If I wanted my 'Smart Apps' on the TV to work, and the TV doesn't have an audio output other than ARC, I would buy a Roku and use that instead.
There's just no world in which enabling HDMI-CEC makes sense because of how flawed it is.
Really, your A/V receiver should have audio setting called 'ARC' and when you switch your TV to an input other than input 1 (ARC), then it will automatically start pumping audio down the connected ARC line. It should not need or utilize HDMI-CEC in any way. But, that's the absurdity known as HDMI.org