I am running a Roku TCL TV through a Yamaha receiver with a Harmony remote. The remote is set up to turn on the TV and receiver at the same time but half the time I have no sound. This is remedied by turning off/turning on the TV. Hard to troubleshoot because sometimes it works properly, so I know ARC is working. Just wondering if anyone had any thoughts about what may be causing this.
ARC/CEC doesn't always work the way one wants it to. In my family room, I have to power on my Yamaha AVR before turning the TV on, or the TV remote will not control the AVR volume, although I almost always get sound. In my bedroom, again a Yamaha AVR, it always works fine regardless of what is turned on first. But my last AVR in that room (still a Yamaha) often had ARC issues and many times it was a constant game turning devices on and off trying to get it to work. I finally gave up and switched to optical. But with the latest AVR replacement (I needed 4K support) ARC has been flawless. . You might see if there's a firmware update for your Yamaha that might help. Be aware that with the older Yamaha AVRs it's a real pain to upgrade the firmware. You have to burn the firmware onto a CD, then play it in a CD player connected to the AVR via optical. I've never tried it on my older receiver. My latest one has network access, so it can be easily updated over the air.
Dan Roku Stick (3600), Ultra (4640), Premiere (3920), Insignia 720p Roku TV, Sharp 4K Roku TV, Nvidia Shield, Windows 10 Pro x64 running Serviio and Plex on a wired Gigabit network.