I did some troubleshooting this evening and think I figured it out. I tried other HDMI cables but still no sound. I took the unit to another TV and tried it and I did get sound. I took the unit back to the original TV and used the same cable I was successful with but still no sound. I went back to the TV it worked on and duplicated the audio settings on the original TV but still no sound. I then started adjusting the audio settings on the original TV and finally got it to work. But then I turned off/on the TV and it didn’t work. L Strange because both TVs are Vizio V series, just different sizes.
What I eventually found was that once the unit was powered on, the sound would not work, but if I changed the input to a TV channel and then back to the input for the Atari, the sound would work. I was able to recreate this multiple times. So as long as I switch to the TV input and back to the Atari, the sound will work.
Something is definitely wonky with the audio on the Atari unit because I have a PlayStation and a Commodore64 mini hooked up too and they work fine every time. but I can live with it since I know how to make it work now.