Software Updater fails to let me update packages my package manager is aware of

[BloodyIron]

Very frequently aptitude will know about new updates from the repos I use, but when I use Software Updater, it reports there are no more updates to apply. I have to revert to using apt at the CLI to update my packages. This really breaks the GUI UX of the environment, and while I am capable of dealing with this, many others users are not, and this should not be an incomplete experience. It's been like this for multiple years now across multiple versions of Ubuntu.

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: update-manager 1:20.04.10.5
ProcVersionSignature: Ubuntu 5.4.0-65.73-generic 5.4.78
Uname: Linux 5.4.0-65-generic x86_64
ApportVersion: 2.20.11-0ubuntu27.16
Architecture: amd64
CasperMD5CheckResult: skip
CurrentDesktop: ubuntu:GNOME
Date: Tue Feb 16 13:29:25 2021
ExecutablePath: /usr/bin/update-manager
InstallationDate: Installed on 2019-03-08 (711 days ago)
InstallationMedia: Ubuntu 18.10 "Cosmic Cuttlefish" - Release amd64 (20181017.3)
InterpreterPath: /usr/bin/python3.8
PackageArchitecture: all
ProcEnviron:
 LANGUAGE=en_CA:en
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=en_CA.UTF-8
 SHELL=/bin/bash
Python3Details: /usr/bin/python3.8, Python 3.8.5, python3-minimal, 3.8.2-0ubuntu2
PythonDetails: /usr/bin/python2.7, Python 2.7.18, python-is-python2, 2.7.17-4
SourcePackage: update-manager
UpgradeStatus: No upgrade log present (probably fresh install)