This is great info! For those of us who got similar problems in MacOS, life was a bit more difficult, but Larry's general idea still applies.
Apple doesn't allow a user to create a new directory under root, but one can follow steps listed in Creating root-level directories and symbolic links on macOS Catalina | Der Flounder (wordpress.com) to create a symbolic link named "attachment" and put the pdf there. The mere presence of /attachment/Form1116ScheduleB.pdf will allow TurboTax to proceed with e-filing.
