I also did submit a request and got a generic answer asking me to subscribe for updates as to which devices were supported or not.
Hard to say if this is HBO's fault or LG's. I'm leaning heavily towards HBO.
I was looking at a 55UH850V, but need HBO Now installed in the OS. I'm assuming, since HBO Go is missing, that HBO Now is MIA too? This would be a deal breaker for me if other brands feature it in their OS.