I have just installed the Tempo Planner add-on in my JIRA Cloud environment. I have an existing SCRUM project with sprints defined. If I select the 'Planning' view under the team, then select 'Iterations' from the hamburger menu on the far right, the panel shows the sprints from my scrum board. However, if I attempt to drag one of these sprints onto the timeline, it is not allowed.
Going the opposite direction, I created a new iteration in Tempo Planner, but that iteration does not appear on my SCRUM board, so there is no way to associate tasks with it.
I must be missing something here .....