Is the cable connected to the back of the TV connected to a standard HDMI port, or one that is specifically labeled as ARC?

It’s connected to the ARC port which for some reason is HDMI 2 on this TV. “TV not recognized” 

Also connected it to HDMI 1 to just make sure but that didn’t work either. 

Hmm, that is odd. I can see several distinct possibilities.

First, I’d double check that the software is updated on this TV. It’s possible that the version of CEC is older, and needs updating.

Next, I’d try a different cable. It’s possible the HDMI cable in use is pre HDMI 1.4, and is incapable of carrying the necessary data. Unfortunately, at least in my experience, cables aren’t often labeled, so you, as the consumer, has little chance of identifying which version of HDMI it supports. If you feel the need to purchase a new cable, look for HDMI 2.1 compliance. 

Next, I’d try turning off CEC (which is the container for ARC) on the TV, then turning it back on. I’ve found that in some situations, a toggle works, and certainly shouldn’t hurt. 

Finally, I’d try a simple reboot of the TV itself, by unplugging it from power for two minutes (not just turning it off with a remote or power button), and then plugging it back in.