ROKU remote for Roku streaming stick 4K, 3820X2, is sluggish and undependable for both volume changes and muting. My cousin in another city, and so another TV and internet provider, has exactly this problem as well. So this has to be a ROKU hardware or software issue. I even bought a new streaming stick, but it has the same problem exactly. Sometimes volume and mute control go away for several seconds, but then come back. This is not the way past Roku remotes behaved. Again, I know others with same issue right now.