DiscoveryPlus app will not stream video when going through pihole due to DNSSEC in pihole

Pi-hole logs all queries received (assuming you don't have logging disabled or privacy level set to record nothing).

If you see queries and they aren't blocked, then Pi-hole isn't blocking anything coming from that client.

Use these tools to ensure you are looking in all the right places for blocked domains:

Another troubleshooting step - change the upstream DNS server used by Pi-hole and see if your problem clears.