· When deploying an operating system to a new computer with multiple disks, the operating system may not deploy to the expected volume. As a workaround, configure the Format and Partition Disk step to set the DestinationLogicalDrive variable to the drive letter of the volume that should be targeted.
I assume that this is just a beta bug so this will probably be fixed in the initial release. I guess that this has something to do with the new ztidiskpart.wsf script. The documentation for the new features will be documented in Beta 2 according to the Release notes.