Add a rule like this right after your authentication rule.
Prepend Realm\ to Username
Puts the domain name in front of the user name
Authentication.IsAuthenticated equals true AND
Authentication.Realm does not equal ""
Set Authentication.UserName = Authentication.Realm
This will put domain into the logs:
It can also be used for rules like:
Authentication.UserName is in list Exception #1: Users or Groups
I'd have to see the entire log definition. There is probably a missing quote or the column headers have become mis-aligned.
The log should definitely import if the field is in the identical place.