Hi,
the configuration is pretty straightforward. This is mine:

overlay memberof
memberof-group-oc groupOfNames
memberof-member-ad member
memberof-memberof-ad memberOf
memberof-dn cn=Manager,dc=my_base_dn
memberof-dangling ignore
memberof-dangling-error 80
memberof-refint FALSE

If you can afford a sequence of
stop -> slapcat -> drop db -> slapadd 
everything gets populated as desired.

I can help if you are concerned to understand why I chose these parameters.

Remember that in dealing with overlays, order matters! So be careful in the order you choose in instantiating them.
Regards
Marco