CX- Orders Date Changed By User field not Updating while Bulk Update of Orders

We have enabled a Bulk Update option in CX Orders from Action dropdown where from on screen UI we can update multiple fields in different Orders at the same time and have written a field trigger on a field called Date Changed By User which captures the Users name in that field whoever updates the Requested Date in Orders.

The issue faced is whenever the user is Bulk Updating Requested Date of multiple Orders the Date Changed By User still remains blank and nothing is coming but if we change the date from screen of that particular Order then its recording the User details.