Cloneprep log originally found in C:\Windows\Temp\vmware-viewcomposer-ga-new.log have been revoked in View 7.12.
It is now merged with 'debug' log file found in agent machine at C:\ProgramData\VMware\VDM\Logs\Debug*.log. You can check debug log file to check cloneprep related activities.
Regarding the failure of post-sync script, If you use a scripting language that needs an interpreter to run the script, the script path must start with the interpreter executable. For example, instead of specifying C:\script\myvb.vbs, you must specify C:\windows\system32\cscript.exe c:\script\myvb.vbs.