RAP Application EMail Template CDS Data Source picks old value before save.

[#1]

I have a RAP Read Only application with a button made with CDS Custom Entity.
This throws a popup with value help for user to pick a new departmentcode.

At the METHOD save_modified I am calling the email template created in SE80, the CDS view in email template is the Root CDS View which joins my custom table with sales tables.

The custom table has new departmentcode field which is getting updated.
How do I get the new departmentcode in email CDS instead of old departmentcode please?