Hi Neal,
Good tip, decided to check it out. Looks like users are imported with the right casing (we have a bit of both in AD apparently, but all are imported with their original casing to the YR user db), but I see a small discrepancy in the ykmaps table; the 'value' column stores users in the format of
'user@DOMAIN.com' (the domain name is in caps), however this is also how the domain entry is listed YR virtual appliance setting so it could be unrelated. In the user list, the 'User DN' lists the DC in lower case though, even though it is specified in caps everywhere else that I can see.
When troubleshooting, authentication succeeds regardless of username casing. Not quite sure where to go next. The only 'problem' I see with the current situation is that I am unable to unassign Yubikeys from users, as the user list page doesn't read the config properly. The auto-provisioning works and I am able to authenticate, I just can't see that provisioning has been completed without querying the Postgre DB directly. (I assume I'd be able to remove mappings from here as well, but I'd prefer not have to do that). I'll post a support ticket and see if Yubico have any suggestions.