Permissions are not set correctly on created directories

I have the following in my syslog-ng.conf for options:

options {
    stats_freq(60);
    flush_lines(500);
    #flush_timeout(10000);
    time_reopen(10);
    time_reap(5);
    log_fifo_size(536870912);
    chain_hostnames(off);
    log-msg-size(65536);
    use_dns(no);
    keep_hostname(yes);
    use_fqdn(yes);
    dns_cache(off);
    dns-cache-size(2000);
    dns-cache-expire(87600);
    create_dirs(yes);
    perm(0640);
    owner(root);
    group(splunk);
    dir-perm(2750);
    dir-owner(root);
    dir-group(splunk);
    threaded(yes);
};

However, instead of 2750 for the directory permissions, I'm seeing

d-wSrwxrwT. 10 root splunk      4096 Mar 28 14:07 ise

[root@molecule8-mfaine data]#  stat -c '%a' ise
5276

I would expect:
drwxr-s---. 2 root splunk      4096 Mar 28 14:11 ise

Where are these permissions coming from?

Thanks,
Mark

______________________________________________________________________________
Member info: https://lists.balabit.hu/mailman/listinfo/syslog-ng
Documentation: http://www.balabit.com/support/documentation/?product=syslog-ng
FAQ: http://www.balabit.com/wiki/syslog-ng-faq