WinPhone operating system has a number of limitations which, in their turn, bring some limitations to Sync. This article contains details on how Sync works due to these limitations.
- Files are copied when opening them in other apps.
When you open file in another app, the file is actually copied to that app. As a result, that app works on a copy of a file and all changes you make are not reflected in the file which is stored in Sync. To sync changes to other peers you'll need to send the modified file back to Sync. - Deleted files are not deleted from other peers.
When you delete a file from WinPhone it actually simply "un-syncs" it from WinPhone. It will not send command "Delete this file on all peers as user deleted it". - Sync cannot access files of other applications.
As a result, you cannot sync files which are stored in other applications unless you transfer them to Sync explicitly - or save them to the Library first (Sync has access to Library). - Not working in the background.
Sync cannot transfer data in the background. It needs to be open to transfer data. So if you are using backup for your pictures, you need to open Sync to let it actually transfer your pics.