I now have a Roku 3810 Streaming Stick+ attached to my LG UH615A TV. I ran the remote setup and I could hear the music and then I heard it stop as expected. The power and volume down work fine but the volume up mutes the TV and if I press it several times I get the TV tuner menu from the LG itself.
My regular LG remote works fine. The Chromecast with Google TV that I used to use worked as well.