PGP Desktop Invisible Silent Enrollment eliminates the typical enrollment screens PGP Desktop users would see during the enrollment process.  Once a user logs in to the system, no screens are displayed and all the enrollment processes are handled in the background such as User creation, drive encryption, sending of recovery tokens to PGP Universal Server.
To implement that, one of the requirement is that the option PGP_INSTALL_DISABLESSOENROLL must be set with the value 0.

More information on that requirement can be found here: 

However, if PGP_INSTALL_DISABLESSOENROLL=0 is set, the Windows Roaming profile will no longer function correctly and the profile will not be saved on the profile server.