DNS not being verfied

I’ve followed the documentation and set up all the necessary DNS records and now I’m facing this weird issue.

When clicking on the “Verify records” button I see that all the NS records briefly get “Verified” (green checkmark and tooltip says verified) then they switch back to “Not verified”, one moment later the TXT record does the same and switches back to “Not verified”.

Here’s the response from the hosted-zone-setup call that is being made (domain redacted for privacy):

Call before it shows that records are verified:

{
    "success": true,
    "domain": "send.mydomain.tld",
    "dnsRecords": b
        "ns1.klaviyo.com",
        "ns2.klaviyo.com",
        "ns3.klaviyo.com",
        "ns4.klaviyo.com",
        "klaviyo-site-verification=VjhB4C"
    ],
    "applied": false,
    "status": 1,
    "verificationAlertLevel": null
}

Here it verified all the NS records:

{
    "success": true,
    "domain": "send.mydomain.tld",
    "dnsRecords": b
        "klaviyo-site-verification=VjhB4C"
    ],
    "applied": false,
    "status": 1,
    "verificationAlertLevel": null
}

And then all the NS records went back to Not verified and TXT got verified:

{
    "success": true,
    "domain": "send.mydomain.tld",
    "dnsRecords": b
        "ns1.klaviyo.com",
        "ns2.klaviyo.com",
        "ns3.klaviyo.com",
        "ns4.klaviyo.com"
    ],
    "applied": false,
    "status": 1,
    "verificationAlertLevel": null
}

And finally back to where we started, all records not verified:

{
    "success": true,
    "domain": "send.mydomain.tld",
    "dnsRecords": b
        "ns1.klaviyo.com",
        "ns2.klaviyo.com",
        "ns3.klaviyo.com",
        "ns4.klaviyo.com",
        "klaviyo-site-verification=VjhB4C"
    ],
    "applied": false,
    "status": 1,
    "verificationAlertLevel": null
}

Any help would be much appreciated!