Software Updater not showing third-party repository with "signed-by" tag

[Mike Jing]

Since apt-key is now deprecated, I followed various guides and moved all third-party repository keys to /etc/apt/keyrings/, then added the "signed-by" tag to the corresponding source lists. After that, those third-party repositories no longer show up in the "Other Software" tab in Software Updater.

/home/jing>lsb_release -rd
Description: Ubuntu 22.04.1 LTS
Release: 22.04

/home/jing>apt-cache policy update-manager
update-manager:
  Installed: 1:22.04.9
  Candidate: 1:22.04.9
  Version table:
 *** 1:22.04.9 500
        500 http://archive.ubuntu.mirror.rafal.ca/ubuntu jammy/main amd64 Packages
        500 http://archive.ubuntu.mirror.rafal.ca/ubuntu jammy/main i386 Packages
        100 /var/lib/dpkg/status

ProblemType: Bug
DistroRelease: Ubuntu 22.04
Package: update-manager 1:22.04.9
ProcVersionSignature: Ubuntu 5.15.0-46.49-generic 5.15.39
Uname: Linux 5.15.0-46-generic x86_64
NonfreeKernelModules: nvidia_modeset nvidia
ApportVersion: 2.20.11-0ubuntu82.1
Architecture: amd64
CasperMD5CheckResult: unknown
CurrentDesktop: XFCE
Date: Mon Aug 22 18:27:09 2022
InstallationDate: Installed on 2018-10-23 (1399 days ago)
InstallationMedia: Xubuntu 18.04 LTS "Bionic Beaver" - Release amd64 (20180426)
PackageArchitecture: all
SourcePackage: update-manager
UpgradeStatus: Upgraded to jammy on 2022-08-21 (1 days ago)

[Julian Andres Klode (juliank)]

Reassigning to correct package, and confirmed. So while [arch=amd64] works fine [signed-by=...] does not which is odd. Neither are *properly* supported in software-properties: sources.list options are not exposed at all; it's unclear what happens if you modify them.