I discovered this exact same issue, but with a slightly different environment. Perhaps it's not an Ubuntu bug but an issue with the kernel?
The brightness keys work in Windows. In linux, I can still adjust the brightness using the power manager slider despite the keyboard hotkeys not working. I am using the Lenovo Yoga C740, with my primary OS as Debian Buster. The brightness up and down keys (F11, F12) do not emit keycodes when pressed, even though holding down Fn and pressing F11 I am able to emit the function key behavior. These issues persist when using Ubuntu 20.04 through a live usb. I wrote a summary of my issues here: https://udia.ca/posts/2020/06/lenovo_c740/#hotkey-diagnosis -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1872311 Title: Brightness hotkeys not working on Lenovo S740 Status in linux package in Ubuntu: Confirmed Bug description: Brightness hotkeys (Fn + F11 for decrease and Fn + F12 for increase) do not work on Ubuntu 20.04 and Lenovo S740 laptop. The brightness hotkeys did not work on 19.10 either. I followed the guide here: https://wiki.ubuntu.com/Hotkeys/Troubleshooting In "Step-by-step Troubleshooting", none of the steps (1-7) did produce any reaction to brightness change key combinations. However, I am able to change the laptop screen brightness through the brightness applet. ProblemType: Bug DistroRelease: Ubuntu 20.04 Package: linux-image-5.4.0-21-generic 5.4.0-21.25 ProcVersionSignature: Ubuntu 5.4.0-21.25-generic 5.4.27 Uname: Linux 5.4.0-21-generic x86_64 ApportVersion: 2.20.11-0ubuntu26 Architecture: amd64 AudioDevicesInUse: USER PID ACCESS COMMAND /dev/snd/controlC1: elias 1447 F.... pulseaudio /dev/snd/controlC0: elias 1447 F.... pulseaudio CasperMD5CheckResult: skip CurrentDesktop: ubuntu:GNOME Date: Sun Apr 12 16:12:01 2020 InstallationDate: Installed on 2019-11-19 (144 days ago) InstallationMedia: Ubuntu 19.10 "Eoan Ermine" - Release amd64 (20191017) MachineType: LENOVO 81RS ProcFB: 0 i915drmfb ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-5.4.0-21-generic root=UUID=101c7da4-860d-4496-ae06-d98699795f9a ro quiet splash vt.handoff=7 RelatedPackageVersions: linux-restricted-modules-5.4.0-21-generic N/A linux-backports-modules-5.4.0-21-generic N/A linux-firmware 1.187 SourcePackage: linux UpgradeStatus: Upgraded to focal on 2020-04-04 (7 days ago) dmi.bios.date: 03/10/2020 dmi.bios.vendor: LENOVO dmi.bios.version: BYCN33WW dmi.board.asset.tag: NO Asset Tag dmi.board.name: LNVNB161216 dmi.board.vendor: LENOVO dmi.board.version: SDK0J40709 WIN dmi.chassis.asset.tag: NO Asset Tag dmi.chassis.type: 10 dmi.chassis.vendor: LENOVO dmi.chassis.version: Lenovo Yoga S740-14IIL dmi.modalias: dmi:bvnLENOVO:bvrBYCN33WW:bd03/10/2020:svnLENOVO:pn81RS:pvrLenovoYogaS740-14IIL:rvnLENOVO:rnLNVNB161216:rvrSDK0J40709WIN:cvnLENOVO:ct10:cvrLenovoYogaS740-14IIL: dmi.product.family: Yoga S740-14IIL dmi.product.name: 81RS dmi.product.sku: LENOVO_MT_81RS_BU_idea_FM_Yoga S740-14IIL dmi.product.version: Lenovo Yoga S740-14IIL dmi.sys.vendor: LENOVO To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1872311/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
