I’ve just logged into my licence details without any verification, as far as I’m aware you’ve always needed a code to view someone else’s licence details on-line.
From what you’ve said it looks like the last time you just entered their details as if it was the drivers themselves checking their own licence details rather than you checking someone else’s licence details, it sounds like this time you’ve clicked on the link to check someone else’s details, in which case you will need a code.
Obviously to use their details to view their licence details you need their permission.