I'm having an odd issue with my optical out volume control. I have the 43" KU6300 from 2016 connected to a Vizio SB3851-CO sound bar, and I've managed to get the volume to change while using TV apps. Once I switch to an HDMI input, I lose the volume control from the universal remote, but there's still sound out of the soundbar. I managed to find a way around this by attaching my HDMI inputs to the sound system as blue-ray players in the universal remote setup, which allows volume control when using the attached port, but stops the TV from turning on the devices when selecting that HDMI port. And since I can only set up two connected systems for the universal remote, I still don't have volume control for the third HDMI port. Is there a way to have the TV control the sound bar volume while using both the TV apps and the HDMI ports, without setting up the TV as stated above?
I've reset the TV, reattached all the devices, and updated it to the latest firmware as well, to rule out any software bugs.