BackupAssist imaging jobs utilise the Microsoft Windows imaging engine to backup and write your data.
As some of you may already be aware, there is a known Microsoft issue when using the Windows imaging engine to back up to a destination drive that is utilising 4K bytes per cluster. This typically relates to the larger (>2TB) USB hard drives that are now becoming more common. Some hard drives can be reformatted using 512 bytes per cluster rather than 4K bytes per cluster but unfortunately not all have this option.