NextDNS CLI Using Backup WAN on UniFi DMP

I recently deployed the NextDNS CLI on my UniFi DMP, everything is working perfectly and I can see all my clients in the logs.  However, I’ve noticed the source IP count has been steadily increasing on my backup WAN and when I hover over items in the log I can see it’s using the backup WAN.  My UDMP is set up with the primary in ETH9 (wan port) and backup in ETH8 (tagged switch port).  I have the UDMP set in failover only mode, not load balanced.  Has anyone else run into this issue and/or found a solution?