Distribution List Admin Delegation Unable to Add Users

Using 6.0.3 I created an admin distribution list and gave the list the "Distribution List" view and granted the following rights:

getAccountInfo
adminConsoleDLRights
getDistributionList
createDistributionList
getAccount
listAccount

All that worked fine for a while. However, now members of that list cannot use the search window to look for users - searches do not return anything. Entering the addresses manually seems to work.

I'm not sure when this stopped working. The only thing that has changed is that I extended the LDAP to add Posix attributes.

Any thoughts?