Primary Plusnet DNS server (212.159.13.49) isn't resolving a specific host but secondary is fine

[#1]

Dear Plusnet Support,

Something fishy is going on with your primary DNS server in that I am unable to resolve the following host (member.vitality.co.uk) via it, but can via the secondary one.  Details are below:

Would appreciate it if someone could look into it ASAP.  

Regards

C:\Users\XXXX>nslookup
Default Server: cdns02.plus.net
Address: 212.159.13.50

> member.vitality.co.uk.
Server: cdns02.plus.net
Address: 212.159.13.50

Non-authoritative answer:
Name: vitality.wip.online2.pruhealth.co.uk
Address: 217.135.160.116
Aliases: member.vitality.co.uk

> server 212.159.13.49
Default Server: cdns01.plus.net
Address: 212.159.13.49

> member.vitality.co.uk.
Server: cdns01.plus.net
Address: 212.159.13.49

*** cdns01.plus.net can't find member.vitality.co.uk.: Non-existent domain

[#2]

Correction.. .now I can't resolve this host on any of the plusnet DNS servers except for the safeguard ones.  I am also able to resolve via google public DNS.

Anyone else having issues with DNS resolution at the moment on the plusnet servers?

C:\Users\xxxxx>nslookup
Default Server: UnKnown
Address: 192.168.5.4

> member.vitality.co.uk.
Server: UnKnown
Address: 192.168.5.4

Non-authoritative answer:
Name: member.vitality.co.uk

> server 212.159.13.50
Default Server: cdns02.plus.net
Address: 212.159.13.50

> member.vitality.co.uk.
Server: cdns02.plus.net
Address: 212.159.13.50

*** cdns02.plus.net can't find member.vitality.co.uk.: Non-existent domain
> server 212.159.6.9
Default Server: cdns01.plus.net
Address: 212.159.6.9

> member.vitality.co.uk.
Server: cdns01.plus.net
Address: 212.159.6.9

*** cdns01.plus.net can't find member.vitality.co.uk.: Non-existent domain
> server 8.8.8.8
Default Server: google-public-dns-a.google.com
Address: 8.8.8.8

> member.vitality.co.uk.
Server: google-public-dns-a.google.com
Address: 8.8.8.8

Non-authoritative answer:
Name: vitality.wip.online2.pruhealth.co.uk
Address: 217.135.96.82
Aliases: member.vitality.co.uk

> server 212.159.6.10
Default Server: cdns02.plus.net
Address: 212.159.6.10

> member.vitality.co.uk.
Server: cdns02.plus.net
Address: 212.159.6.10

*** cdns02.plus.net can't find member.vitality.co.uk.: Non-existent domain
> server 212.159.6.10
Default Server: cdns02.plus.net
Address: 212.159.6.10

> server 213.120.234.42
Default Server: indnsc92.bt.net
Address: 213.120.234.42

> member.vitality.co.uk.
Server: indnsc92.bt.net
Address: 213.120.234.42

Non-authoritative answer:
Name: vitality.wip.online2.pruhealth.co.uk
Address: 217.135.160.116
Aliases: member.vitality.co.uk