I tested on both amd64 and i386 as detailed in the linked post in the original description. I installed both amd64 and i386 variants of Ubuntu 16.04.3 in parallel in separate VMs and experienced (from a user perspective) the same issue. The difference being what appstreamcli returns on each...
On amd64:- alan@cleanamd64:~$ appstreamcli search steam Identifier: ri-li.desktop [desktop-application] Name: Ri-li Summary: a toy simulator game Package: ri-li Icon: ri-li_ri-li.png ---- On i386:- alan@cleani386:~$ appstreamcli search steam Identifier: steam.desktop [desktop-application] Name: Steam Summary: Application for managing and playing games on Steam Package: steam ---- Identifier: ri-li.desktop [desktop-application] Name: Ri-li Summary: a toy simulator game Package: ri-li Icon: ri-li_ri-li.png ---- alan@cleani386:~$ -- You received this bug notification because you are a member of Desktop Packages, which is subscribed to appstream in Ubuntu. https://bugs.launchpad.net/bugs/1718453 Title: Cannot install steam on a clean 16.04.3 machine Status in appstream package in Ubuntu: New Status in gnome-software package in Ubuntu: New Bug description: I noticed the following community member had a problem installing steam. I reproduced it on 16.04.3 clean install i386 and amd64. https://www.youtube.com/watch?v=24NH3Ry22Dg Install 16.04 amd64 or i386 Install all updates via software updater Open Ubuntu Software Search for steam. No results for Steam found. Yet steam is in the repository as an i386 deb - but it doesn't show up in Ubuntu Software on either amd64 or i386 installs. Also discussed at https://ubuntu.labix.org/t/ubuntu-software-deb-install-issues/81 ProblemType: Bug DistroRelease: Ubuntu 16.04 Package: gnome-software 3.20.5-0ubuntu0.16.04.5 ProcVersionSignature: Ubuntu 4.10.0-35.39~16.04.1-generic 4.10.17 Uname: Linux 4.10.0-35-generic i686 ApportVersion: 2.20.1-0ubuntu2.10 Architecture: i386 CurrentDesktop: Unity Date: Wed Sep 20 15:46:02 2017 InstallationDate: Installed on 2017-09-20 (0 days ago) InstallationMedia: Ubuntu 16.04.3 LTS "Xenial Xerus" - Release i386 (20170801) SourcePackage: gnome-software UpgradeStatus: No upgrade log present (probably fresh install) To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/appstream/+bug/1718453/+subscriptions -- Mailing list: https://launchpad.net/~desktop-packages Post to : [email protected] Unsubscribe : https://launchpad.net/~desktop-packages More help : https://help.launchpad.net/ListHelp

