Scenario set up:
1. Background task is responsible for scheduling 5 tile updates, each displaying a "unread message header".
2. "Unread messages" are stored in app settings and are updated regularly by main process (when it is in foreground).
Scenario, in chronological order:
1. Maintenance trigger fires, background task starts and manages to post 2 out of 5 tile updates before being preempted;
2. Main application (in foreground) updates the list of "unread messages", changing all 5 of them, it then updates the tile appropriately;
3. task A gets CPU time, posting the remaining 3 tile updates it needed to do; overwriting fresh updates from application and leaving the tile in inconsistent state (2 updates from new batch, 3 updates from the old batch).