Status transition in workflow task status is not allowed when a new status is added a new behavior is added in a Workflow task, and it is added in a category.
Customer opens a new change order, with the above category, when he tries to change the task status setting it with the new added behavior, it's not saved because the status transition is not allowed.
However there is no place in UI to set the workflow task transitions
Service Desk manager 14.x / 17.x
There is no way to add Workflow status transition through UI