CEC between different manufacturer's devices is always hit or miss. And sometimes it's even different between different products from the same company. I had all sorts of problems with my Samsung TV and a Yamaha AVR, but when I replaced the AVR with a new Yamaha, it's worked perfectly since. I don't think there's anything "wrong" with any of your devices. It's just the way they decide to work together. Sometimes a firmware update will help, and sometimes it makes it worse. Again with my gear, Samsung had a number of updates that really messed up CEC and ARC, but then they finally got it nailed down.
Dan Ultra (4640), Ultra (4670), Ultra (4800), 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.
Thanks. Unfortunately (and predictably, I suppose) no updates/downloads available for the Sony. The TCL Roku still receives updates. Whether this will ever improve interacting with the Sony is, as gamblers might say, a crapshoot.
TCL 4K Roku TV S403 / 7101X Wired ethernet 100 Mbps give or take