Certain Safari users may notice Safari chooses to open the CSV file as a text file rather than saving it or opening it your spreadsheet software.
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By far, the easiest way to solve this problem is just to download the CSV:

Once you're stuck looking at the CSV contents, just click Command/Control + S

If you want to automatically have your computer download the file so you can easily open it with your spreadsheet software, you'll need to do a bit of work to set properties to have the file download appropriately:
​https://www.blackmanticore.com/1c569206754935dacb0dc6b89ca818b8
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As an alternative, some are so frustrated with this Safari issue they just open Chrome when they want to download CSVs.