Accounts created recently with Virgin Money have a 10 digit customer ID, which doesn’t work on the Virgin online banking flow. For all other Virgin accounts (which have a 7 digit customer ID), it should work.
This is happening because Virgin have been bought by Clydesdale and Yorkshire Bank group and they’re in the process of merging the two organisations.
Please, get in contact with Virgin Money to address this with them directly. This link takes you to Virgin's Money Contact page.