Go to the settings menu in your iOS device.
Select the Safari browser from the list.
Scroll to the Data and Privacy section and deactivate "prevent cross-site tracking".
Clear Website Data
Scroll a bit further and click the "Clear History and Website Data" field
Close your Apps
Go to your task manager and close the Grape app and your Safari browser.
Now you should be all set. Restart the Grape App and log in with SSO.