I am using CLoudmounter downloaded from the web on a MacBook Pro. I have several drives mounted from Google and Dropbox. When I double click on an .XLSX file I get the following error:
Excel cannot open the file 'SPT Billing Differences.xlsx' because the file format or file extension is not valid. Verify that the file has not been corrupted and that the file extension matches the format of the file.
However, if I go to the Google Drive folder via the context menu (View on Google Drive.com) the file opens up correctly.