Ok, guys, @HeyBurt is right, apparently the formatting part got right but the verification doesn't. I've just updated the plugin to try to solve this. I've added more debug verbosity to help me fix it in case this update doesn't address the issue.
For those that want to test it, there's a small trick to limit the preclear routine to the first 4Gib of the drive. In <server name> > Tools > Preclear, hit Help in the menu bar, than click Start preclear. In the dialog, at the bottom, you have to select Enable Testing (just for debugging). This will limit all read/write routines to the first 4Gib, and as the name say, speed up the debugging process. If it's successful, I still recommend a normal/full pass, even if the disk has been zeroed before.
In case of issues with the new version, please send me the logs.