When running the collection, not able to post the data using the selected JSON file

I am not able to run the collection for the POST request while values are fetched from the selected JSON file. Here TagTypes_CreateOrEdit_name's value is getting generated into the Request Body but for TagTypes_CreateOrEdit_id's value for null is being replaced by TagTypes_CreateOrEdit_id.

It does work when values are entered into the BODY section, I’m also able to run GET, PUT, DELETE methods using file select.

Screenshot (136)
Body tab: