I'll look at the bug; in the meanwhile, you may want to fix your configuration by adding

chase-referrals no

overlay chain chain-uri <the referred URI with no DN> chain-idassert-bind <info to allow proxyauthz of users> # ...

See slapo-chain for details. Another option is to use

chase-referrals no rebind-as-user yes

Thanks Pierangelo

The fact that it worked under debug mode was throwing me off. Referrals have been fixed and it's working as expected now.

Neil