When the task manager is set to be ordered manually, the order isn’t saved between reboot (or even when plasmashell crashes). That would be a welcome addition as an usability feature.
*** Bug 403410 has been marked as a duplicate of this bug. ***
Can't reproduce, for me it always saved the tasks order.
I can reproduce this this issue using the following steps: 1. Enable "manual" sorting for the task bar in its settings. 2. Manually change the sorting of some windows in the task bar using drag & drop. 3. Run "plasmashell --replace" After plasmashell restarted I got the original order of entries again instead of the manually changed one.
*** Bug 459482 has been marked as a duplicate of this bug. ***
*** Bug 464685 has been marked as a duplicate of this bug. ***