LDAP provider for old Jira (6.4)

[WERTBON1789]

I'm currently running Jira 6.4 and an old OpenLDAP instance for that thing alone because I couldn't get it to work via the LDAP provider.
Does anybody have an idea on what to do exactly to get it to work?

Main Problem:
Authentik doesn't provide a memberUid attribute for groups and using member has the problem that Jira only searches with the RDN of the user, not the FDN, so member doesn't pass the filter that Jira uses.

There is the solution of just assigning memberUid in the custom attributes, but that's also cumbersome and really annoying.
Is there any better solution?