An SSIS package is invoked via DTEXEC.EXE from a web application. The package uses a File System Task to make a copy of an Excel template file to be used as the Excel desti
Using Process Monitor reveals that ISServerExec.exe is trying to save a buffer to C:\Users\Default\AppData\Local\Microsoft\Windows\Temporary Internet Files. When the limited user account is given access and permissions under C:\Users\Default, everything works.
This explains why an interactively logged-in user or a local admin account was able to write Data Flow records to the Excel file, but a regular batch login was not able to do so. This is an undesirable behavior of the SSIS Excel Destination.