Re-link IP address to v6 (or link multiple)

Hi,

New to NextDNS, this has probably been asked and answered many time so apologies -- please forgive the newbie...

I set up my first profile and had no issue linking my IPv4 address.

Since then I now have a v6 address from my ISP and a /48 PD I can use. My router is set up now with the IPv6 addresses of NextDNS -- BUT for the life of me I cannot make the profile link to my v6 even though I've verified (using Curl) that next DNS can see me using the v6 address. I've also tried setting up a new profile and linking that but same issue, still the v4 shows.

I can't tell whether the v6 has linked but the UI can only show one (and chooses the first), or whether for whatever reason my browser / Mac are insisting on sending v4 all the way to the DNS.

I am new to everything -- new to my router / networking environment (Unifi), new to NextDNS, new to IPv6... steep learning curve. If anyone can point me in the right direction, I'd appreciate it. 

Thanks

Alastair