Thank you for sharing more information. That is unusal. You should be able to add the expansion for fom (to the sweep result) result using the addsweepresult script command. Once you add it and run the sweep then you will see it in the GUI Results. I was able to do so in the same file from the article you mentioned above. What happens when you use the addsweepresult command? Do you also get the same error? In the first screenshot that you shared, you were using getresult which resulted in the error message.You have to use addsweepresult.
You can also do it manually in the Edit Parameter Sweep window? Can you find it in the Parameter Sweep window as shown below?