It doesn't look an error to me.
Calculated metrics setting allows you to change the formatting (i.e. decimal, percent, etc.) to present in the desired format on the workspace dashboard.
A Comma Separated Values (CSV) file is a plain text (unformatted) file that contains a list of data, therefore, .csv export is supposed to remove any formatting which was changed to display on workspace dashboard. Similarly, when using "copy to clipboard" it copies value as text (unformatted) else you will have HTML copied with it.
To test it, download the same report in PDF format. it should not remove calculated metrics formatting while download. As PDF file preserves the original graphic appearance on workspace dashboard.
Hope that helps.
Thanks,
Asheesh