Migrating server results in user password issues

[greep elem <g33plm@gmail.com>]

Hi all, 

Hopefully someone can point me in the right direction as I appear to be going around in circles at this stage.

I am attempting to migrate from one server running OpenLDAP 2.4.9 configured with old style slapd.conf to a new server running openldap 2.4.23 with the dynamic cn=config setup.

I've successfully exported / imported via slapcat and slapadd and using phpLDAPadmin I can browse all my users.  The issue I run into is the use passwords do not work when I try to log into services (e.g. IMAP).   

Using phpLDAPadmin I perform a password compare and it returns a mismatch.  

Looking at the slapcat output for a user, the "userPassword" is afaik md5 run though base64 and presented as such but once bas64 is decoded it matches what phpLDAPadmin reports if I export the user.

userPassword:: e01somedandomdataPT0= 

I docode this :
     user@server.tld$ perl <<EOF
     > use MIME::Base64;
     > print decode_base64('e01somedandomdataPT0=') . "\n";

     > EOF
     {MD5}thisisahash==

Exporting the user in phpLDAPadmin and compare it's reported userPassword to the above perl output and they match.  As they match I am at a loss as to why the password is not accepted when I try to login via IMAP or check password in phpLDAPadmin.   As soon as I change the password, the account works find and the user can log in.

Any help greatly appreciated, as I would rather not have to reset user passwords!