After you rebuild a Windows Server 2012 server all the storage spaces will default to read-only mode. Here are two commands to set them back to read/write mode.
Get-StoragePool | Where-Object {$_.IsReadonly –eq $True } | Set-StoragePool –IsReadonly $False
Get-VirtualDisk | Where-Object {$_.IsManualAttach –eq $True} | Set-VirtualDisk –IsManualAttach $False