I have set up our active directory with delegated LDAP authentication (first) and JIRA internal directory second. Then when a customer creates an account in a service desk, he cannot log in. I can see that the user is created, but they are not able to log in.
If I switch it around though, they are then able to log in.
My suspicion is that it is trying to authenticate against AD if its set up as the first auth method.