Thanks to everyones help, I am back up and running under 10.0.1.
My last issue is that when I power cycle (off then on) the TV and AMP, I lose video from the RPI4 and have to reboot it. I am using the video port towards the front of the board because I get no video at all from the rear video port. In fact it seems as if the PI is shut down because I don't see it on the network.
I suspect that this has something to do with CEC but not sure which config I should have. I already uncommented the disable CEC in config.txt, not sure if there other configs I should change.