Created Unassigned: SP2013SP1 + Jan2016CU - UP Sync stuck at starting synchronization full or increment sync [22168]

SP2013SP1 + Jan2016CU - UP Sync stuck at starting synchronization full or increment sync when I leave the script update the Sync Service in SP to the SP_services account. I fixed the issue by commenting the flowing at the CreateUserProfileServiceApplication function
#UpdateProcessIdentity $profileSyncService
#$profileSyncService.Update()

this tested on 2 env. one on Azure IaaS and another on on client production On-premises

Regards,
Mahmoud Hamed