Just went through the same X1 client box (RNG150N) nonsense. Tried codes that worked in a previous Control4 job, no worko. Tried 4 different Control4 IR drivers (older, newer, custom) -- nothing. I even tried the direct connect flasher input on the back of the box with a mono cord. Nope.

It seems like it's an IR receiver issue. When moving the flasher around the front I was able to do a channel change when I covered up the flasher with my hand in certain spots, but was unable to get this to consistently work.

In reading other messages here, it seems that the RNG150N is made by two companies: Arris and Pace. Apparently, the Pace boxes are the ones with the issues.