The Timetable feature is only available for students with individual timetables that are found from: https://timetable.soton.ac.uk/
If your timetables are not available on the main service then you will not be able to view your timetable in the app.
However, should your timetable be present and it is not showing in the app. Please fully log out of the app by going to settings and clicking log out and fully close the running app, then log back into the app as normal.
If this still does not work for you, please contact ServiceLine: https://sotonproduction.service-now.com/soton/it.do