This improvement request is based on this bug, which makes the test search fail via the "Configuration" tab.
The above options like the "Active Directory Connector" configuration, helps in resolving the problem for "Delegated" configuration too by using the following workaround, as suggested by a customer:

I found a workaround, by tweaking the database (cwd_directory_attribute) table.
I set:
ldap.pagedresults to 'true' (was 'false'
I added 'ldap.pagedresults.size' with value '999'.

This makes the directory attribute similar for 'AD' and 'Deletaged AD'.