Had this issue during the building of a Windows 10 reference image using build 1607.
During the Windows Update Pre-Application Installation the build would stop and progress no further. The update was the Definition Update for Windows Defender – KB2267602 (Definition 1.63…)
Looking at thethe download did not start and the progress was at 0%.
I have included the update KB######### to allow the Windows 10 1607 build to communicate with the local WSUS server.
I have added the Definition Update to the exclusion list in theproperty using WUMU_ExcludeKB as shown below:
After kicking off a new reference build the task sequence continued on with no issues.