protected mode not available in Acrobat Standard 2017?

I've upgraded from Acrobat Reader 2017 to Acrobat Standard 2017.

In Acrobat Reader it's possible to 'Enable Protected Mode at Startup'

Unfortunately in Acrobat Standard this option is not available.

I've tried to activate it via Windows Registry:

HKLM\SOFTWARE\Policies\Adobe\Adobe Acrobat\2017\FeatureLockDown

bProtectedMode = 1 (REG_DWORD)

Unfortunately that doesn't make a difference in the UI and I'm still not sure if it's enabled or not.

According to the Acrobat Application Security Guide Acrobat X isn't sandboxed. However version X is quite old. What's about the 2017 release?Protected Mode — Acrobat Application Security Guide

I would be happy if an Adobe employee could clarify if Protected Mode is available for Acrobat Standard 2017.

Thanks for your support,