This appears to be intentional and was done by the change in lp:~jbicha/software-properties/dont-show-in-gnome-system-settings (not by me). So software-properties-gtk should not show in GNOME Control Center but software-properties-gnome should.
This appears to be intentional and was done by the change in lp:~jbicha/software-properties/dont-show-in-gnome-system-settings (not by me). So software- properties- gtk should not show in GNOME Control Center but software- properties- gnome should.