One workaround would be to buy a device called "Sideclick" from Amazon or elsewhere. It will give you 8 extra buttons that can be programmed from the tv remote to control volume and mute and power of your tv. I have one and it works great.
My Roku voice remote WAS working perfectly. It would turn my TV off and on, change the volume, etc. I lost the ability to change the volume on my TV today, but I can't reconnect the remote to my system to get the volume control back. I tried reconnecting the remote multiple times, but with no success. Is there anything you can do to help me fix it?
My TV is a Hisense (I don't know the exact model) and my system is a Roku Ultra.