Effective Start Date not Update When Use REST API to Update Assignment

Hi All,

I am trying to do employee assignment change though REST API: Update a worker assignment

here is my paload:

Effective-Of:RangeMode=SET_EFFECTIVE_START;RangeStartDate=2025-02-06;RangeEndDate=4712-12-31;

{    "ActionCode": "ASG_CHANGE",    "JobCode": "Technical-8",    "DepartmentName": "Card Centre"}

After update I found the Effective Start Date not update while the same attribute in assignment is updated.

I think the action should change to 'Assignment Change' becasue I update the ActionCode too.

When do the same update operation in UI, it works as expectaion (both effective and action code updated)

May I know why?

Thanks in advance!