If you have an Nvidia GPU in this laptop then it's possible and even likely the HDMI port is wired to Nvidia and not Intel. This means the feature depends on the Nvidia driver installed.
When you say: > but all the HDMI output devices are listed as "unplugged" can you please explain what you are looking at there? ** Package changed: xorg (Ubuntu) => ubuntu ** Changed in: ubuntu Status: New => Incomplete -- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to xorg in Ubuntu. https://bugs.launchpad.net/bugs/1857821 Title: external HDMI monitor always "unplugged" Status in Ubuntu: Incomplete Bug description: Hello my Ubuntu friends, I can no longer play sound over my external HDMI connected TV. The image displays perfectly, but all the HDMI output devices are listed as "unplugged" I have spent a huge amount of time trying every solution that Internet searching will bring but this has changed nothing. I have tired all available video drivers, including Xorg and NVIDEA 396.26, 340.107, and 384.130. This failure is recent because in the past I could play both audio and video through the HDMI connector. The laptop is dual boot with Windows 10 and the HDMI works perfectly on that OS, although I rarely use it... I am wondering if upgrading my Xubuntu to the latest LTS could potentially solve this issue, but I fear such an update since I depend on this computer and an outage would be very hard for me... Any thoughts would be great. Thanks for making Linux great! Bob ProblemType: Bug DistroRelease: Ubuntu 16.04 Package: xorg 1:7.7+13ubuntu3.1 ProcVersionSignature: Ubuntu 4.4.0-170.199-generic 4.4.200 Uname: Linux 4.4.0-170-generic x86_64 ApportVersion: 2.20.1-0ubuntu2.21 Architecture: amd64 CurrentDesktop: XFCE Date: Sun Dec 29 17:00:14 2019 InstallationDate: Installed on 2015-05-11 (1693 days ago) InstallationMedia: Xubuntu 15.04 "Vivid Vervet" - Release amd64 (20150422.1) SourcePackage: xorg Symptom: display UpgradeStatus: No upgrade log present (probably fresh install) To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+bug/1857821/+subscriptions -- Mailing list: https://launchpad.net/~touch-packages Post to : touch-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~touch-packages More help : https://help.launchpad.net/ListHelp