This is actually a bug caused by the Microsoft Excel program.

Workarounds:

Option A
  1. Download the iif file
  2. Save it to your computer without opening the file first
  3. Open Excel
  4. Click on the Data tab
  5. Click From Text
  6. Set the Text Files drop down to All Files
  7. Locate and select the iif file
  8. Click Open and follow the Text Import Wizard step

Option B: Download and open the file directly in Notepad
Option C: Select the QuickBooks (.iif) File - Drop Box option when exporting
Option D: Select the QuickBooks (.iif) File - Email option when exporting