Noticed that my TV updated to 9.2.0 build 4111-30 late last night and now my volume controls are extremely slow. When I click on volume up/down or mute, it take a few seconds for the TV to acknowledge. Same issue with using the Roku app on an Android phone. I even re-paired my remote to the TV. I'm assuming the latest update broke the volume control. I can see the white LED light flicker with each click but doesn't respond every time. TV is not connected to any other speakers or receivers. Anyone ever experience this? Do I have to wait for another update to fix this?
Try using the option in Settings>System>Power>System restart to restart your TV and see if this helps. I would also recommend unplugging your wireless router/modem for a few minutes to fully reboot them.
Once the router/modem are back online, check your TV's network connection once more to confirm it is connected (for mobile app control ability), then try adjusting the volume again.
The volume only went up or down 1% every second, after doing this it goes up and down 1.5% every second, not a huge improvement. Making things worse is that the volume can not be muted while moving volume up or down. This issue will be addressed in future updates because it is very annoying.