Hi All

I'm looking for some guidance around an error I'm seeing when I sync users to AD. I see an error around an LDAP constraint and user principal name, the user name for students start SXXXXXX and I'm only seeing this error on users that start S3XXXXX, all the rest work fine. I've exported all drivers and import them into my dev environment, Meta/Vault/AD setup and I don't see the error at all. My eDir trees and AD aren't representative.
Has anyone seen this before and can tell me where to look? I've had this problem before when two things were trying to update the single valued attribute, but I have no idea here as all users are the same. I didn't set up AD in the prod environment, so I have limited visibility. I thought at first that the driver was at fault, but I'm not seeing it in DEV, where should I be looking?

Any thoughts or idea's, even fixes will be greatly received?.
Cheers
Jon