VLAN and Apple Mobile Profile not reporting

Gateway: Ubiquiti/UniFi) Dream Machine Pro 

I have some VLAN and NextDNS configuration which work fine (e.g my IoT VLAN and my LAN VLAN both have a different configuration and that's seems to work fine since the DNS server is different.

The problem, some other VLAN with they own config/DNS server doesn't seems to have any traffic at all according to NextDNS.

I did setup the specific DNS server as per NextDNS settings in the VLAN DNS server config (no other DNS server, same public IP than the order VLANs)

some client on this VLAN even have a Apple Mobile Profile for NextDNS made from the specific NextDNS configuration but yet this configuration report data at all

- for one of the IOS client on this specific VLAN, (and with MDM profile) the correct DNS server is reported in settings/WiFi/BSID name>i (icons for details informations)