I have an LG TV paired with a Harmony Hub and have SmartThings as my brain.
I purchased harmony because I wanted voice automation of my LG TV. I tried several times to get the intergration right on my own but ended up having to call Harmony support.
Turns out my LG TV has a Direct TV ready app allowing the use of Direct TV without a set Top box. The device is called Direct TV RVU. It interferes with the normal operation of Harmony. My intergration required the addition of extra steps and delays. If you also have this setup, inbox me and I can provide you the steps I have if needed.