If I search for "ubuntu-restricted-extras" with the search of ubuntu software, does not find it!

Taking the example of "ubuntu-restricted-extras" if you look for in Ubuntu Software is off but finds other packages, while with Ubuntu Software Center and the Unity Dash, there are no problems.

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: ubuntu-software 3.20.1+git20160617.1.0440874.ubuntu-xenial-0ubuntu1~16.04.1
ProcVersionSignature: Ubuntu 4.4.0-31.50-generic 4.4.13
Uname: Linux 4.4.0-31-generic i686
NonfreeKernelModules: nvidia_uvm nvidia
ApportVersion: 2.20.1-0ubuntu2.1
Architecture: i386
CurrentDesktop: Unity
Date: Sun Aug 7 19:13:29 2016
InstallationDate: Installed on 2016-04-21 (107 days ago)
InstallationMedia: Ubuntu 16.04 LTS "Xenial Xerus" - Release i386 (20160420.1)
SourcePackage: gnome-software
UpgradeStatus: No upgrade log present (probably fresh install)