No error messages, I get the typical "Started customization of VM..." but the guest never reboots or goes through a sysprep operation nor does vsphere confirm that customization was successful. I looked in the guestcust.log and could find nothing to suggest an error or that any part of the customization failed. Hoping I'm not alone here, this is a plain vanilla install of Windows 10, nothing fancy added or configured.
vSphere Client version 5.5.0 build 3237766
vCenter Server version 5.5.0 build 3142196
VMware ESXi, 5.5.0 build 3568722
VMware tools are current and running
guestcust.log attached.