Google Docs, Sheets and Slides reports are not saved to Stormboard. Instead, they are saved to a specific folder created by Stormboard in your Google Drive.
To find your report in Google Drive, look for the Stormboard folder in the top-most folder of your Google Drive:
Each Storm will have its own folder within the Stormboard folder.
In each Storm's folder is a Reports folder that contains each Google report generated by Stormboard for that Storm.
You can also find the report by clicking the Open in Google Drive link in the top right corner of the report editor in your Storm.