The patch indeed seems to have fixed the issue. But now I've updated to XUbuntu 22.04 with xfce4-panel 4.16.3-1 and the bug is back, which means that the also needs to be applied there.
-- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1968942 Title: Sometimes windows are missing in panels tasklist To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/xfce4-panel/+bug/1968942/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs