No error message is returned.
The issue looks to be caused by the folders having a very old CreationTime such as 12/31/1969.
A Process Monitor of the StorageFileWatch.exe process on the Enterprise Vault server may show the following.
Event Class: File System
Operation: QueryNetworkOpenInformationFile
Result: SUCCESS
Path: \\Server\Archiving\Enterprise Vault Stores\Vault Store Ptn1\2010
CreationTime: 12/31/1969 8:00:00 PM
LastAccessTime: 1/19/2012 10:47:25 AM
LastWriteTime: 1/19/2012 10:47:25 AM
ChangeTime: 7/1/2015 7:14:35 AM
Set the creation time on the folder and all sub-folders for the year path. This can be accomplished using PowerShell cmdlets.
Once the folders have a proper Date created as view with File Explorer the StorageFileWatch process should be able to scan the folders for files to collect.