This happens with devices that are classed as tablets – for some bizarre reason as per https://support.microsoft.com/en-us/kb/2959188

and can be modified using https://technet.microsoft.com/en-us/library/dn660972.aspx

Here’s a screenshot of what it should look like in WSIM

or in xml

<settings pass=”specialize”>
<component name=”Microsoft-Windows-UnattendedJoin” processorArchitecture=”amd64″ publicKeyToken=”31bf3856ad364e35″ language=”neutral” versionScope=”nonSxS” xmlns:wcm=”http://schemas.microsoft.com/WMIConfig/2002/State”>
<Identification>
<Credentials>
<Username>
</Username>
<Domain>
</Domain>
<Password>
</Password>
</Credentials>
<JoinDomain>
</JoinDomain>
<JoinWorkgroup>
</JoinWorkgroup>
<MachineObjectOU>
</MachineObjectOU>
</Identification>
</component>
<component name=”Microsoft-Windows-Shell-Setup” processorArchitecture=”amd64″ publicKeyToken=”31bf3856ad364e35″ language=”neutral” versionScope=”nonSxS” xmlns:wcm=”http://schemas.microsoft.com/WMIConfig/2002/State”>
<ComputerName>
</ComputerName>
<ProductKey>
</ProductKey>
<RegisteredOrganization>
</RegisteredOrganization>
<RegisteredOwner>
</RegisteredOwner>
<DoNotCleanTaskBar>true</DoNotCleanTaskBar>
<TimeZone>Pacific Standard Time</TimeZone>
<ShowPowerButtonOnStartScreen>true</ShowPowerButtonOnStartScreen>
</component>