demm
Thank for your help.
I will wait a fix to the bug. I am managing to work in the current situation.
In fact, now I'm using both monitors with limitations but I can live with it :-)
Hope for a quick fix

    Any improvement when running kquitapp5 plasmashell && plasmashell once the system has fully booted up?

    Running "kquitapp5 plasmashell && plasmashell" works perfect.
    It recovers my initial configuration of destop. Minor adjustments are needed (some icons lost).
    Until official fix to bug, this solution works great.
    Thank you very much Demm

    • demm replied to this.

      jotade70 @raul338
      Can both of you test patched qt5-base? Patch used is from this bug report:
      https://bugreports.qt.io/browse/QTBUG-86604

      sudo pacman -U http://kaosx.tk/repo/build/qt5-base-5.15.1-2-x86_64.pkg.tar.zst

      Since the patch is not approved yet, this version won't move from the build repo, until it is tested as fixing the multi screen issue.

          demm
          I have installed. After reboot I reconfigured the monitor layout and wallpapers again. The config was kept after 3 reboots.

          I think this fix is working

            Hello Demm.
            The patch does not work for me. The system behave just like at the beginning.
            I keep using the command you listed-

            One more rebuild for qt5-base is up, this time with the change that started this issue reverted:

            sudo pacman -U http://kaosx.tk/repo/build/qt5-base-5.15.1-3-x86_64.pkg.tar.zst

              demm
              Hello Demm.
              With the last patch I have recovered the original functionality.
              Everything seems to work OK after 2 reboots.
              Thank you.

                demm Today after a reboot, It happened again!

                The bug report seems to be fixed with a new QT version. I'll have to try with that compiled

                  A patch is now accepted upstream (no longer taken from any bug report), one more rebuild is up, again, please test & report back:

                  sudo pacman -U http://kaosx.tk/repo/build/qt5-base-5.15.1-4-x86_64.pkg.tar.zst

                    demm
                    No problems with that last patch. Everything works as usual.
                    Regards