Google Drive does not detect internet connection
Used to have the same problem.
In my case, google drive was trying to open the document using Sheets app, but the Sheets app was allowed to access documents only via WiFi connection. Go to Sheets/Setings and uncheck "Transfer files only over Wi-Fi" checkbox. Be aware, that similar "Transfer files only over Wi-Fi" checkbox is also in Drive app, but this affects only Drive app, not the Sheets app.