I have set up an Active Directory server directory to sync with (Read Only w/ Local Groups) - I can disable/re-enable the directory under user management, trigger a sync, and all users will appear (approximately 350).
However the users will disappear every time, sometimes this happens immediately, sometimes it may take five minutes.
I have noticed that once I have used an account from my active directory (as an issue reporter) it is added to the internal directory. However shortly afterwards, the username gets crossed out and has "(inactive)" listed underneath it.
EDIT: I am trying to sync up my users as customers only. That way they are able to log into the customer portal with their AD credentials, and I don't have to send them an invitation.
SETUP:
JIRA Service Desk 3.14.0
JIRA Core 7.11
Running JIRA on-premises (Windows Server 2016) connected to a separate database server running Server 2012 with SQL 2014.