Thanks everyone for the help on this topic. The Vizio techs were ready to replace my TV and Soundbar before I found this post.
My solution involved a bit of surgery on an HDMI cable. Take a knife or razor blade and cut the outer sheathing around one end of an HDMI cable. Once you get this cut, you can open it up and then slide it off or back on the cable to expose the connections of the HDMI. There may also be a foil wrap around the connections that you may have to peel off. Once you get this back you are going to take a knife and cut the connection for pin 13. The color may be different for various brands of cable. Most importantly is finding the 13 pin. Looking on the internet I found 2 conflicting pictures; the first didn't work and the second was successful.
POINT THE END OF THE HDMI CABLE AT YOU. ROTATE SO THE SIDE WITH 10 PINS ARE ON TOP AND THE FEWER 9 PIN SIDE IN FACING BOTTOM. THE 13 PIN IS THE 4TH PIN ON THE TOP, FROM THE RIGHT HAND SIDE.
Simply cut this connection and make sure the cut wire lays straight and doesn't touch any others. BE CAREFUL USING THE KNIFE OR BLADE, YOU CAN EASILY CUT YOURSELF. I took a pair of tweezers and pulled the pin completely out. This isn't necessary but you can do it if you like. Close the cable up, slide the end sheathing back on and secure with a piece of electrical tape, duct tape, or any tape you have.
Plug the repaired end into your TV and the non repaired end into the Arris DCX3600M. Your CEC should work normally.
The good news is that Spectrum is infact upgrading the new 3600M boxes to v8.0 and that includes a new Middleware and OS image that should fix the problem. However, it is going to take several weeks before this will be completed, but some areas are starting to get the new update. Hopefully, you wont have to tamper with someone elses equipment to get ARC working. I personally don't use ARC as can cause problems, but if you do use it, let us know if the new update fixes it. The new OS is v18.10 vs 14.93 or something like that in the previous version.