SharePoint User Group UK

A strange problem that's driving me up the wall. My Site/User profiles - User A enters their manager into their profile, when you view User A's profile page you can see they report to that manager in the Organization Hierarchy. However, when you view the manager's profile page User A doesn't appear under them? If User A changes their manager to someone else, it works fine?

This happens to a set number of users, 10 links out of approx. 60. We've re-imported and migrated the profiles many times and still the same users have the same problem?

Any ideas?

something in the Active Directory for those users which is over writing the properties on import?

The relevant field (Manager) isn't mapped to and AD equivalent, also if that was the case it would work up until the point that it has been overwritten. As mentioned, change to a different manager and it works fine, it just seems to be the relationship between 1 particular user to another.