https://bugs.openldap.org/show_bug.cgi?id=10111
--- Comment #4 from Josh Cox uberthoth@gmail.com --- I realized I needed to alter this line:
dn: olcOverlay=dynlist,olcDatabase={-1}frontend,cn=config
to this line:
dn: olcOverlay=dynlist,olcDatabase={2}mdb,cn=config
on my example here: https://github.com/joshuacox/openldap-overlay-dynlist