.co.uk domain transferred to 123-Reg from another domain registrar. The transfer has successfully completed and the domain now appears in the 123-Reg control panel. However, every time trying to get into Manage your DNS section of the portal produces the following error:
DNS record not available
The domain you have submitted is not available in your account, please try again.
The issue seems to affect some .co.uk domains transferred to 123-Reg. According to the 123-Reg support staff, the issue is some sort of a bug and happens "randomly". The only way to resolve it is to contact 123-Reg support. It only takes them a few seconds to fix this on their end.