Box Sync 4.0 provides detailed user notifications if there an issue syncing a file or folder.
If a collaborator has locked a file on Box and prevented downloads, you will not be able to download and update the file until it is unlocked.
All devices with Box Sync installed.
Locate the file on Box, right-click and select Unlock File. Before the file is unlocked, you can view the name of the person who locked the file. Contact this person to coordinate your changes. Once this file is unlocked, use the "Retry All" button found in the problem file window.