Cdb_diff_iterate doesn't call iter() api

We are using older version of ConfD. I’m seeing issue with cdb_diff_iterate.

I have subscription code for an oper variable ‘status’ which has tailf:cdb-oper;, And is part of a list and key is of type type inet:host;(string)

When cdb_start_session2 is called with lock for this oper variable, i do see that the subscription code is called but the iter() in cdb_diff_iterate is not invoked. Is there a known issue with oper variable indexed by ‘string’ and cdb_diff_iterate, in older version of ConfD.

What might be the reason for not calling iter() api?

This should work, ConfD releases 6.7 and newer contain example showing exactly this, do you have it? In either case, it should work in older releases too, I believe.