NextDNS IP not reachable via COX

I've seen other similar posts. Looks like connectivity via COX / Phoenix area is being blocked. I have two ISPs connected to my Palo firewall - Cox and Verizon. I can reach without issue from Verizon but unable to access via COX - can't ping and no DNS / UDP 53 response. 

Any ideas what could be causing this? Just started this morning (10/26/2024 - 10:53AM / Arizona Time). If I change the route on my firewall to use Verizon, no issue - so not device related or anything like that. I've completely reset me Cox connection and even forced a new dynamic IP - same issue. Any suggestions? I can send traceroutes or whatever is needed but will need to mask / obfuscate my actual public IP assignment.

BTW, NextDNS is fully aware of my IP (updates via DDNS info) - so that part works fine. But cannot send any queries. As I said, different ISP works fine - and I can use any other DNS provider from COX as well (pointed to Cloudflare / OpenDNS via Cox - no issues at all).

Thanks.