This is the solution thanks to chDVRuser and tmm1. They both got me looking into name resolution and I found the modified /etc/hosts file in the container thanks to them. Solution was to remove the hardcoded entries for the host sp.auth..adobe.com.
So between chDVRuser and tmm1 I was able to get enough clues to fix this. Apparently some time in the past I must've edited the /etc/hosts file in the container - unless something does that automatically? I don't recall ever getting into the container to do that, but the file looked like this:
127.0.0.1 localhost
127.0.1.1 cartman
#198.54.122.135 mail.privateemail.com
# The following lines are desirable for IPv6 capable hosts
::1 ip6-localhost ip6-loopback
fe00::0 ip6-localnet
ff00::0 ip6-mcastprefix
ff02::1 ip6-allnodes
ff02::2 ip6-allrouters
# Added by Docker Desktop
# To allow the same kube context to work on the host and the container:
127.0.0.1 kubernetes.docker.internal
# End of section
#
54.68.29.35 sp.auth.adobe.com
44.239.120.244 sp.auth.adobe.com
Note the sp.auth.adobe.com entries at the bottom. The one that starts with 54 was the expired one.
I deleted those 2 lines, saved it, and exited the container. Then I successfully added the source and got 140 channels. I bet when the one cert expired I started losing channels, but is it common for providers to use 2 separate IPs and certs for their TVE range? Seems odd, but possible I guess.
I don't know who to mark for the solution since you both helped me. Aman, if you want to mark one of the posts as a solution that's fine. I appreciate the help, and now I know more than I thought I wanted to about the internals of CDVR 
Thanks!
BTW - sorry for any typos. My laptop is 11 years old and keys are starting to stick or not work. Guess I have to remove 5000 screws and clean the keyboard.