Ronny says that the Husquavarna Viking doesn't run on Windows 8.1, but they've issued a patch to fix it. She also says that the caller probably has an old model, the latest ones can read CDs and thumb drives. Jonathan also has a sewing machine that reads the floppy and he says that Windows 8.1 has new settings for floppy discs that cause issues like that.
Leo also thinks that Windows 8.1 uses a different file format that causes the issue. So Leo thinks that if the sewing machine was used to format the floppy, it could work.