B2 Pro left stereo channel is Mute

Hi, you can have a fault in the mute circuit of the amplifiers, control the mute voltages in the dee circuit Display

Hola, puedes tener una falla en el circuito de mute de los amplificadores, controla las tensiones de mute en el circuito dee Display

In reality the problem is that you got a generic TV which is Dynex and you really need the genuine remote perform all of the required settings and functions perfectly if you're buying also a generic remote you're going to have difficulty with this you have to try multiple settings before that remote is going to work perfectly

You cannot normally mute just certain channels. It's usually all or none. Do you subscribe to the channels that have no sound?

First verify that the mute is disengaged (toggle the mute button). Second, check the sound configuration to make sure the internal speakers are on, or check the sound output to make sure it is going to the inputs of an external audio amplifier (stereo receiver) and that the external amplifier is working. Try a different input source - perhaps the problem is your cable feed or DVD player.
If the internal speakers are on, the volume is up, and you still don't get any sound from a known-good source (TV channel, DVD player, etc.), then try running the sound to a stereo system as described above.
If that works, you may have a shorted speaker amplifier (depending on the set's design, this may blow a fuse supplying power to both left and right amplifiers or a speaker protection circuit will keep the speakers disconnected). These aren't usually hard to repair, but if you find a blown fuse, fix the amplifier before replacing the fuse or you'll just waste another fuse.

Does the distortion ALSO appear when you listen with headphones? If not, the problem may be downstream. The driver for the mute control line to the mute transistors may have a problem. Make sure the mute is off.

Some cables can be ok on test but one of the wires can be loose inside the cable and it will prevent pockets to be sent out and received but will test as ok. not that often but i have seen it before.

You need to have a jumper between the 4 standalone jacks on the right side of the column of stereo connectors. A stereo RCA cable would work for this.

there should be an audio section of your tv
Go through each of your setting s and be sure nothing was changed. goto setup and reset to factory settings. your TV will do something funky and powercycle.
THAT should fix your problem.
if not, is your cable service through your VCR? if so, remove the vcr altogether and connect your cable services directly. All should now be a go.

Always check your cables and connectors on them to make sure the cable is good and the connectors are not loose. This sounds like a bad cable or connection between the line output of your mixer and input to your stereo.

can you share me the current firmware of your KVM switch.