We have some problems with the LDAP lookup plugin.
I’ve checked directly on our LDAP and the user for which the lookup fail is there, with all the attributes we search for.
Component : Lookup Plugin
Misconfigured setup.
After configuring the Lookup you should only have the appropriate keys selected for the type of incident that you will be performing the lookup on.
Remove the Lookup keys which are not in use and reloaded the lookup so not all keys are selected, only they ones you really need.
The Lookup Parameter Keys can be found in the Enforce console page System> Incident Data > Lookup Plugins -> Click on the Lookup Parameters button to open the page.
This may be applicable for other Lookups too.