Block differences not working correctly

Local incremental backups are set for Block differences - hashed but is taking up the same space as a Full backup on the file system.
For one PC I have an incremental backup reported in UrBackup of 2014-7-21 11:24 Incremental Yes Size 26.29KB but if I browse to that folder on the file system the space used is 26.6GB. Browsing that same PCs Statistics in UrBackup I see a total backup size of 49.51GB but the space on the filesystem for that PC is reported as 505GB. This is a fresh install as I filled up the 5.5TB hard drive recently so I decided to wipe and reload but the issue persists. I also have the same issue at our sister site on a Windows 8 box running the server. Any ideas?

Server - Win 7 Pro x64 Urbackup 1.3.2
Clients - Win 7 Pro x64 Urbackup 1.3.1

Hello Random

As far as I know this only works on linux with the btrfs file system.
See this topic Special treatment of .pst files (not .ost files)