Assignment History UE is not giving expected output

Summary:

Hi Folks,

We have created the extract using PER_EXT_PAY_EMPLOYEES_V2_UE as root data group and PER_EXT_ASSIGNMENT_BASIC_HISTORY_UE as child data group.

Extract Employee V2 Assignment ID is threading database item in root DG with Extract Employee V2 Person ID as key attribute in root DG.
In Child DG 'Extract Historical Assignment Person ID' ,'Extract Historical Assignment ID' and 'Assignment Effective Start Date' are key attributes.
All the attributes are not marked as change or always display except key attributes. When we make any changes on assignment level, like job_code changed and run the extract with changed and marked marked attributes then from HISTORY UE we are getting all the attributes which are not even changed.