Hi Amanda
In that Issues tab, top right, there should be a 'Print' link to printit from the browser. But the workbook format you're looking for is like Excel workbook? If so I found another way to try:
In Assessment tab click the "Comprehensive Assessment Report", scroll down to the "Discovered Network Issues" section. It has the same data as in the Issues tab. That table I found I can select, copy and paste into an Excel spreadsheet. Does that give you a workaround that you can work with?
HTH