This DCM cab adds a service dependency on the CCMEXEC service to ensure SMSTSMGR has started first. See the blog article http://www.potentengineer.com/task-sequence-stuck-installing-in-software-center/ for more information.
Update 3rd August 2016 - The CAB has now been updated to match the PowerShell version. Previous the code has been reversed so the wrong dependences were being added.
If you would like the powershell version then see - https://gallery.technet.microsoft.com/Fix-for-Software-Center-b16a6076