Different behavior of cdb_diff_iterate() after upgrade NCS from 3.4.8 to 3.4.12

funciton : int cdb_diff_iterate(int sock, int subid,
enum cdb_iter_ret (*iter)(confd_hkeypath_t *kp,
enum cdb_iter_op op,
confd_value_t *oldv,
confd_value_t *newv,
void *state),
int flags,
void *initstate);
The callback function *iter() in cdb_diff_iterate() is not called when doing some CDB ‘delete’ operations.
It was OK when I used NCS 3.4.8. The flag is ITER_WANT_PREV.
Is there any changes for this function?

As we do ConfD in this forum but are NCS friendly, I suggest you check the CHANGES file that came with that 3.4.12 release for clues.