Secondary monitor black after rotation

[Roger Light]

I have two monitors, a landscape 1680x1050 (main monitor) and a portrait 1920x1080, rotated 90 degrees anticlockwise (secondary monitor). Nvidia graphics card, with the proprietary drivers.

When I log in, the secondary monitor is entirely black. If I move my mouse to the monitor, I can see it. If I try to drag a window to it, I can see the mouse cursor but no window.

If I use Ctrl-Alt-F2 to swap to a console, then swap back to the desktop the problem is resolved and I have a notification stating that kwin restarted desktop effects due to a graphics change.

This is reproducible, it happens every time I log in.

Please let me know if I can provide more details.

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: kwin (not installed)
ProcVersionSignature: Ubuntu 5.4.0-18.22-generic 5.4.24
Uname: Linux 5.4.0-18-generic x86_64
NonfreeKernelModules: zfs zunicode zavl icp zcommon znvpair nvidia_modeset nvidia
ApportVersion: 2.20.11-0ubuntu21
Architecture: amd64
CurrentDesktop: KDE
Date: Tue Mar 24 10:16:47 2020
InstallationDate: Installed on 2018-10-22 (518 days ago)
InstallationMedia: Kubuntu 18.10 "Cosmic Cuttlefish" - Release amd64 (20181017.2)
SourcePackage: kwin
UpgradeStatus: Upgraded to focal on 2020-02-06 (46 days ago)

[Roger Light (roger.light)]

Update:

If I go to System Settings/Display and Monitor, then click "Identify", then only the primary monitor is identified.

I tried disabling the secondary monitor and re-enabling it, and that fixed the problem as well for this session.

[Roger Light (roger.light)]

I can now reproduce this from within the session.

* Starting point - everything is displaying as expected.
* Open System Settings/Display Configuration
* Disable the secondary monitor and click Apply
* Enable the secondary monitor (this will have reverted to landscape mode) and click Apply
* -> The monitor should now display the desktop as normal (although in the wrong orientation in my case)
* Click on "90 degrees anticlockwise" orientation, then click Apply
* -> The monitor will be black, with a visible mouse cursor

The same behaviour is shown going from no rotation to 90 degrees clockwise, or from 180 degrees rotation to either of the portrait orientations, but it works fine going from no rotation to 180 degrees.

[Scarlett Gately Moore (scarlettmoore)]

This bug is very old, if it is still an issue please update the bug with information from a supported release.

[Roger Light (roger.light)]

I'm no longer on 20.04 so can't confirm whether it is still present there (it's still a supported release, right?). It must have been fixed in the interim because it no longer affects me on 23.10. I guess since nobody else seems to have been affected then this can be closed as fixed.

[KDE (kde-community)]

Kubuntu only has support cycles of 3 years for LTS. We just don't have the resources to support 10 year cycles. Though I am working on changing that. Thanks for the update!

[Roger Light (roger.light)]

Ah, yes, sorry I forgot there was difference with the flavours.