Synology DDNS hostname not being picked up by NextDNS servers

I have been using NextDNS for a few years and a Synology NAS for long while.    At some point recently NextDNS servers stopped resolving my Synology DDNS hostname.    nslookup on my Synology DDNS hostname returns 0.0.0.0 when I use the NextDNS servers however nslookup using google or cloudfare dns servers resolve fine.    How do I get this fixed?