So I recently had to rebuild my Server 2012 virtual server. I had storage spaces setup and after I finished the install the Virtual Disk was not mounted. I realized that I was able to bring it all back online, but every restart it had to remount the VHD.

I had decided there must be a way to fix it and decided to see what the properties were within PowerShell. I ran a Get-VirtualDisk which showed me my single VHD (pictured below)

I was thrilled when I saw the IsManualAttach property, with a simple execution of Set-VirtualDisk Data -IsManualAttach 0, I executed a Get-VirtualDisk and verified it took the settings change. After a restart the VirtualDisk was already mounted and resolved my problem with only two PowerShell commands.