01-21-2021 10:23 AM
I have tried so many of the workarounds...Not worth keeping the soundbar if it isn’t going to function without me having to trick it. I downloaded the updated firmware from the vizio support site on a USB drive. I then plugged the USB drive into the soundbar. The firmware updated but that was not the issue.
01-21-2021 10:27 AM
Now that I have learned more about how the soundbar functions I doubt it was actually working before. We weren’t using the tv much and the problem will begin only once you adjust the volume for the first time after tv is turned on. So if I never adjusted the volume the issue wouldn’t happen. Found this one out while troubleshooting more and more.
02-14-2021 05:13 PM
I think it has to be a Verizon issue. I am having the same exact problem with my Bose soundbar. I found this thread while looking for Bose tips. Since multiple brands are having the same exact issue, it has to be a Verizon problem.
My current solution, use HDMI and have the TV control the volume and I have a post it note covering my IR sensor on the soundbar
03-05-2021 12:33 PM
Update: Vizio has come out with a firmware update for M21d-H8 soundbar (18.104.22.168) that has seemingly fixed the MUTE CEC issue that I found. My workaround configuration seems to work fully now for me with the Fios remote. Thanks Vizio!