I have a ROKU3 hooked up to a Samsung TV through an Onkyo receiver. The receiver is meant to control everything and has all inputs going into it with one HDMI cable connecting it to the TV. The problem is that after I have been using the ROKU, the receiver/TV will not switch back to the correct input if I want to play a game or watch a DVD. It get's stuck on the ANYNET+ feature and keeps pulling up the ROKU menu. I have to go into the TV menu and switch the input. I use a Harmony Smart remote to control everything (Except the ROKU of course) and so it's a big pain to have to find the TV remote to go into settings and do this every time.
Go into the Roku system menu, find the control other devices menu, and disable one touch play. This turns HDMI CEC control off from the Roku. If your problem continues after that, the problem lies elsewhere.
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.