I had same issue. I moved my router, which was really close to the IR sensor and it is now receiving the signal properly.
I had been using the roku app on my phone during that time that it wasnt working and that worked fine, was just annoying as a permanent solution because I couldnt use my phone at the same time and had to keep going back to the app to change volume or pause and what not.
Check if you have wifi nearby.... I dont know if IR and wifi interfere but it solved my problem.