Did you connect your TV and you amplifier using the HDMI-ARC (Audio Return Channel)? That's how I connect my Sony TV with my amplifier so when I use the plugin from my Android TV the sounds is sent back thanks to ARC to the amplifier which swith automatically to the right entry, when I stop it and return to my STB HDMI entry the amplifier switch back to the STB entry. I never play with the amplifier RCU.
But my experience with HDMI-CEC is that when you play too much with all those parameter you can have weird behavior and sometimes I even had to unplug replug the HDMI cable and perform a cold start to validate a particular setup.
So perhaps set the HDMI-CEC parameters like you think they should be, cold restart all your installation and check what happens.
Another point if your STB has a kind of Universal RCU some keys are then used to send command directly to the TV an no longer to the STB.
For exemple on VU+ when you define the TV code on the RCU than the volume key sent is to TV and no longer the one from the STB.
Edited by Pr2, 1 December 2020 - 08:29.
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Sat: Hotbird 13.0E, Astra 19.2E, Eutelsat5A 5.0W
VU+ Solo 4K: 2*DVB-S2 + 2*DVB-C/T/T2 (used in DVB-C) & Duo 4K: 2*DVB-S2X + DVB-C (FBC)
AB-Com: PULSe 4K 1*DVB-S2X (+ DVB-C/T/T2)
Edision OS Mio 4K: 1*DVB-S2X + 1*DVB-C/T/T2