Timetable is behindWesterwork fetches your data regularly, but not every second. So a change can take a moment.
Notifications don't arriveInstant push notifications are part of Premium. First check that Premium is active.
Widget shows nothingWidgets only show school data while Premium is active. Without Premium you see a neutral tile to open Westerwork.
App won't load or you're offlineSee a bar saying you're offline? Then your device has no connection. You'll see the data from last time, but nothing new comes in.