I have a Smart (LG) TV that is fed by an (Anthem) AVR having about 5 different sources plugged into it. One of the sources plugged into the AVR is a ROKU (Ultra)
When I try to use the Smart TV features through the ARC ports on TV and AVR, it works fine...UNLESS there is a ROKU connected. I have turned off 1-touch, but there seems to be no option to disable CEC on the ROKU.
If the ROKU is connected to AVR (even if off), there is no sound coming from the TV to the AVR; once the HDMI cable is unplugged from the ROKU it works. I prefer the ROKU interface to WebOS interface, but it looks like I can't have both without heroic measures.
If there were a ROKU model that would play nice, I'd probably get a new one, but as it is, I may be done with ROKUs.
