Can't use long path names in Windows 2016

The description of the setting, as seen in the very article that you linked to, says:

Enabling NTFS long paths will allow manifested win32 applications and Windows Store applications to access paths beyond the normal 260 char limit per node. Enabling this setting will cause the long paths to be accessible within the process.

This means that even after you turn this on, not every application is going to magically start being able to access long paths. Each specific application still has to be coded so as to "opt-in" to this support.

As of the time of this writing, Explorer.exe and cmd.exe are not taking advantage of this yet. (But they will, eventually... just give it time.)

But I have seen Powershell taking advantage of the new feature: