scottklement.com

We are able to create a correct payload (JSON file) which is working correctly in Postman. but when we try to send from an RPGLE we keep getting this error of "{"status":400"message"."Malformed request","additional error".""} SetError()#13:HTTP 1.1 BadRequest"

It must be in the something in the program that we are missing. Has anyone seen this before or point us where we need to look next.

One reason could be that you are not using ccsid 1208 and there are many more .....
If you suspect it's a programming error - posting the relevant code would make it easier for us to help you.

I'd start by examining how you are making the request and looking at the debug file... likely there's a problem there.