If this is still unresolved... You might want to ask Qlik support for help editing the postgres database.
And regarding the LDAP filter, I struggled a bit getting it right but now it works. My settings in the UDC:
Additional LDAP Filter: (memberof=CN=qlik,CN=Users,DC=mycompany,DC=com)
In my case, 'qlik' is a domain-local security group.
Hope this helps.