"Software is up to date" even after refresh, but "apt update && apt upgrade" shows updates

[Nathaniel W. Turner]

The Updates tab shows "Software is up to date". Pressing the reload button on the button bar shows it looking for new updates, the "Software is up to date".

Running "sudo apt update && sudo apt upgrade" however shows 143 upgraded packages:

Reading package lists... Done
Building dependency tree
Reading state information... Done
Calculating upgrade... Done
The following NEW packages will be installed:
  linux-headers-4.15.0-15 linux-headers-4.15.0-15-generic linux-image-4.15.0-15-generic linux-image-extra-4.15.0-15-generic linux-tools-4.15.0-15
  linux-tools-4.15.0-15-generic networkd-dispatcher
The following packages have been kept back:
  nodejs nodejs-dev
The following packages will be upgraded:
  adwaita-icon-theme adwaita-icon-theme-full appstream autofs autofs5 ca-certificates cloud-image-utils command-not-found command-not-found-data cpp-7
  evolution evolution-common evolution-plugin-bogofilter evolution-plugin-pstimport evolution-plugins g++-7 gcc-7 gcc-7-base gcc-8-base gcc-8-base:i386
  gedit gedit-common gir1.2-gdesktopenums-3.0 gir1.2-goa-1.0 gir1.2-harfbuzz-0.0 gjs gnome-calendar gnome-contacts gnome-keyring gnome-keyring-pkcs11
  gnome-online-accounts gnome-settings-daemon gnome-settings-daemon-schemas gnome-todo gnome-todo-common gsettings-desktop-schemas language-pack-en
  language-pack-gnome-en language-selector-common language-selector-gnome lib32gcc1 lib32stdc++6 libappstream4 libasan4 libatomic1 libcc1-0 libcilkrts5
  libevolution libfreetype6 libgcc-7-dev libgcc1 libgcc1:i386 libgfortran4 libgjs0g libglib2.0-0 libglib2.0-bin libglib2.0-data libglib2.0-dev
  libglib2.0-dev-bin libgnome-todo libgoa-1.0-0b libgoa-1.0-common libgoa-backend-1.0-1 libgomp1 libharfbuzz-dev libharfbuzz-gobject0 libharfbuzz-icu0
  libharfbuzz0b libitm1 liblsan0 libmpx2 libnautilus-extension1a libnghttp2-14 libnss-myhostname libnss-mymachines libnss-systemd libobjc-7-dev libobjc4
  libpam-gnome-keyring libpam-systemd libpoppler-glib8 libpoppler-qt5-1 libpoppler73 libpython2.7 libpython2.7-dev libpython2.7-minimal libpython2.7-stdlib
  libqpdf21 libquadmath0 libsonic0 libstdc++-7-dev libstdc++6 libsystemd-dev libsystemd0 libtsan0 libubsan0 libudev-dev libudev1 libxen-4.9 libxen-dev
  libxenstore3.0 libyelp0 linux-generic linux-headers-generic linux-image-generic linux-libc-dev linux-tools-common linux-tools-generic nautilus
  nautilus-data ndiff nmap poppler-utils python2.7 python2.7-dev python2.7-minimal python3-commandnotfound python3-distupgrade python3-software-properties
  python3-update-manager qpdf snapd software-properties-common software-properties-gtk strace systemd systemd-container systemd-sysv ubuntu-docs
  ubuntu-drivers-common ubuntu-release-upgrader-core ubuntu-release-upgrader-gtk ubuntu-settings ubuntu-wallpapers ubuntu-wallpapers-artful
  ubuntu-wallpapers-bionic ubuntu-wallpapers-zesty ubuntu-web-launchers udev update-manager update-manager-core xserver-xorg-input-libinput yelp
143 upgraded, 7 newly installed, 0 to remove and 2 not upgraded.
Need to get 81.3 MB/244 MB of archives.
After this operation, 379 MB of additional disk space will be used.
Do you want to continue? [Y/n] n
Abort.

After cancelling the "apt upgrade" and pressing reload in the Gnome Software Updates tab, it still indicates "Software is up to date".

I would expect the Gnome Software Updates UI to show that there are updates available.

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: gnome-software 3.28.1-0ubuntu1
ProcVersionSignature: Ubuntu 4.15.0-13.14-generic 4.15.10
Uname: Linux 4.15.0-13-generic x86_64
ApportVersion: 2.20.9-0ubuntu4
Architecture: amd64
CurrentDesktop: GNOME
Date: Mon Apr 16 11:07:27 2018
EcryptfsInUse: Yes
InstalledPlugins:
 gnome-software-plugin-flatpak N/A
 gnome-software-plugin-limba N/A
 gnome-software-plugin-snap 3.28.1-0ubuntu1
SourcePackage: gnome-software
UpgradeStatus: Upgraded to bionic on 2018-03-06 (40 days ago)

[Nathaniel W. Turner (nturner)]

Note: same behavior even after dealing with the "kept back packages":

Reading package lists... Done
Building dependency tree
Reading state information... Done
Calculating upgrade... Done
The following NEW packages will be installed:
  linux-headers-4.15.0-15 linux-headers-4.15.0-15-generic linux-image-4.15.0-15-generic linux-image-extra-4.15.0-15-generic linux-tools-4.15.0-15
  linux-tools-4.15.0-15-generic networkd-dispatcher
The following packages will be upgraded:
  adwaita-icon-theme adwaita-icon-theme-full appstream autofs autofs5 ca-certificates cloud-image-utils command-not-found command-not-found-data cpp-7
  evolution evolution-common evolution-plugin-bogofilter evolution-plugin-pstimport evolution-plugins g++-7 gcc-7 gcc-7-base gcc-8-base gcc-8-base:i386
  gedit gedit-common gir1.2-gdesktopenums-3.0 gir1.2-goa-1.0 gir1.2-harfbuzz-0.0 gjs gnome-calendar gnome-contacts gnome-keyring gnome-keyring-pkcs11
  gnome-online-accounts gnome-settings-daemon gnome-settings-daemon-schemas gnome-todo gnome-todo-common gsettings-desktop-schemas language-pack-en
  language-pack-gnome-en language-selector-common language-selector-gnome lib32gcc1 lib32stdc++6 libappstream4 libasan4 libatomic1 libcc1-0 libcilkrts5
  libevolution libfreetype6 libgcc-7-dev libgcc1 libgcc1:i386 libgfortran4 libgjs0g libglib2.0-0 libglib2.0-bin libglib2.0-data libglib2.0-dev
  libglib2.0-dev-bin libgnome-todo libgoa-1.0-0b libgoa-1.0-common libgoa-backend-1.0-1 libgomp1 libharfbuzz-dev libharfbuzz-gobject0 libharfbuzz-icu0
  libharfbuzz0b libitm1 liblsan0 libmpx2 libnautilus-extension1a libnghttp2-14 libnss-myhostname libnss-mymachines libnss-systemd libobjc-7-dev libobjc4
  libpam-gnome-keyring libpam-systemd libpoppler-glib8 libpoppler-qt5-1 libpoppler73 libpython2.7 libpython2.7-dev libpython2.7-minimal libpython2.7-stdlib
  libqpdf21 libquadmath0 libsonic0 libstdc++-7-dev libstdc++6 libsystemd-dev libsystemd0 libtsan0 libubsan0 libudev-dev libudev1 libxen-4.9 libxen-dev
  libxenstore3.0 libyelp0 linux-generic linux-headers-generic linux-image-generic linux-libc-dev linux-tools-common linux-tools-generic nautilus
  nautilus-data ndiff nmap poppler-utils python2.7 python2.7-dev python2.7-minimal python3-commandnotfound python3-distupgrade python3-software-properties
  python3-update-manager qpdf snapd software-properties-common software-properties-gtk strace systemd systemd-container systemd-sysv ubuntu-docs
  ubuntu-drivers-common ubuntu-release-upgrader-core ubuntu-release-upgrader-gtk ubuntu-settings ubuntu-wallpapers ubuntu-wallpapers-artful
  ubuntu-wallpapers-bionic ubuntu-wallpapers-zesty ubuntu-web-launchers udev update-manager update-manager-core xserver-xorg-input-libinput yelp
143 upgraded, 7 newly installed, 0 to remove and 0 not upgraded.
Need to get 0 B/244 MB of archives.
After this operation, 379 MB of additional disk space will be used.
Do you want to continue? [Y/n] n
Abort.

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Sebastien Bacher (seb128)]

Thank you for taking the time to report this bug and helping to make Ubuntu better. This particular bug has already been reported and is a duplicate of bug 1709725, so it is being marked as such. Please look at the other bug report to see if there is any missing information that you can provide, or to see if there is a workaround for the bug. Additionally, any further discussion regarding the bug should occur in the other report. Feel free to continue to report any other bugs you may find.