DNS failing to resolve specific sites

My PiHole has started to not resolve Amazon.com and Reddit.com. Everything else I normally go to works fine. If I set my DHCP to bypass the PiHole and go to my local DNS server, the sites resolve fine.

System is set up to use the OpenDNS servers at 208.67.222.222 and .220.220, with a conditional forward for my local 192.168.0.0/23 network and local domain name (that is the correct mask, I am using 192.168.0.0-192.168.1.255), resolv.conf points to my AD DNS server and to the OpenDNS servers, my AD DNS uses OpenDNS as the forwarder as well. Using any device on my network, I can resolve local services (e.g. notes.domain.local resolves to my locally hosted Trilium service) and external sites (e.g. google, pi-hole.net) but for some reason Amazon and Reddit don't resolve. Both sites respond to ping on both end user devices as well as the pihole server SSH console.

I have disabled blocking, I have disabled all of the blocking sites, I have restarted PiHole, flushed and restarted the DNS cache, have regex whitelisted the domain names. One frustrating aspect is I don't see the requests coming in on the query log. I have flushed DNS on the Windows DNS server, as well as on my workstation, no joy. At this point I have my DHCP service set to my AD DNS server for name resolution as I can't figure out why just these two domains are affected.

Other than the above configs, I think my PiHole is relatively stock. Any ideas are appreciated!

If the queries are not showing in the query log, it means Pi-hole is not involved in the issue.

Probably your upstream DNS server (OpenDNS), or a firewall is blocking the requests.

Turns out it was SurfShark. Have a router based VPN setting so I have a dedicated IP (work requires a whitelisted IP, ISP keeps changing mine). For some reason, Amazon and Reddit would use the ns1.surfshark.com name servers, but all other sites would use standard ones. Not sure what's up with that. Dropped the config and recreated it, and now it works fine.