Hey! Let me use your CEC thread.
I experience problems too. I have Panasonic TV with Marantz AVR connected through HDMI ARC. STB VU+ Duo4K and Playstation4 connected to TV. HDMI CEC is working except these cases.
1. When I switch TV source to PS4, the input switches for about 2-3 seconds and then changes back to input of the STB. Like the STB wouldnt want to let go... Only way to switch to another source is to shut the STB down or unplug it. (the issue is intermittent, is there a way to see hdmi cec logs? the plugin has some logging option but only serial console?!)
2. This issue might be HDMI working as designed. When I have all devices connected through the AVR and I turn one ON -> TV and AVR switches ON, tv switches input to the one of AVR, but AVR wont - I have to switch input manually. On top of that STB may block switching to another input - issue 1.
Any suggestions guys? Thanks.