slapd-ldap and backend errors

While setting up and testing new 2.4 infra (2.4.33), I've come across the situation where the proxy (slapd-ldap) doesn't pass LDAP_UNAVAILABLE back to the client when the backend slapd goes away. Is this behavior configurable on the proxy, something along the lines of chain-return-error?

Example: connect to the backend slapd and ldapsearch a long-running query, then shut down slapd and the client provides the proper "error can't contact." Duplicate that behavior while searching against the proxy and you simply get a truncated list of entries with no errors.

Thanks, John