I've been having the same problem since Dec. 29. It's happening with both of my Roku players and Vizio TVs. I don't remember the model of the other Roku player because it's upstairs, but it's a Roku-tie. This one is model 3941X-Roku Express 4K+ with software version 10.5.0. I don't feel comfortable providing the rest of the information publicly. Anytime I open a channel or app there is no sound. To trouble shoot the issue, I turn off the TV and then turn it back on again and then there will be sound.
Has anyone gotten any information from Roku about this yet? I usually have to switch to a different input on my tv, then switch back to Roku to get sound. It’s odd. For example, when I select Netflix, as I’m scrolling through selections, the automatic previews will play with sound, and once I select a something and it loads, there will be no sound. Like I said, I have to switch my tv input to something else, the back to my Roku input to get sound.