Re-synchronizing a Box will rebuild its entire structure. You can access it via the "Data" drop-down menu or by double-hitting 'r' on a keyboard..
Whenever triggered, this functionality pulls all Tasks into the Gantt chart based on the Box's scope, and completely rebuilds Gantt's WBS based on the scheduling rules.
In Boxes with numerous tasks, synchronization might be time and memory consuming. Therefore use this only when you identify problems and your tasks do not synchronize correctly. Sometimes a simple browser Refresh (F5 or Ctrl+R) will do the trick.
Box data is stored in the App's cache after you trigger synchronization. If the Box is not opened for more than 24 hours the cache will be automatically cleared and a full synchronization will be triggered.
Only a user with a minimum Box admins security role can trigger the re-sync.
Task synchronization screen: