On September 25th 2017, Apple changed the user-agent that is used with communicating with the Apple iOS software signing server, which stopped all (except MacOS) versions of iTunes from working (Apple has since released the fixed iTunes versions). Since Blancco's iOS erasure also works thru Apple servers, this caused an issue where iOS device erasure was failing around 22%.
Blancco has released Blancco Mobile Device Eraser (BMDE) version 3.3 that among other things, addresses this issue with the iPhone erasure. The update is available via Blancco's OTA (Over-The-Air) download server, by downloading and updating the version straight from the Blancco Mobile Device Eraser software over internet connection.
To update the software from previous versions, e.g. from 3.2.4, logout and log in to BMDE to trigger the OTA check/download, then click the status bar download icon to install the update once it has finished downloading. After installing, restart the BMDE software to reboot to the updated version.