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to this setting:
when it's changed to not foget forget to press "Publish" button:
You need to repeat those steps for post-functions of other transitions, to make sure there's a correct allocation of assignee to the issue (i.e. transition "approve" should automatically reassign the issue back to a requesting user via the use of post-function as well).
5) Remember about saving workflow changes and next step is to assign Vacation Manager issue types (if you have already created it) to a workflow copy:
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After user presses "Create" button, his line manager is to see:
Manager decided to approve request:
In HR Statistics it is possible to see newly made request:
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