Why does the estimate for the Ideal Line begin so high in my Burndown Chart?
The starting point of the ideal burndown line is pinned to the maximum task estimate or to do value for the entire iteration. Essentially the start point can go up, but the start can never down.
For example: On day 1, there are 40 hours in task estimates so the ideal line starts at 40. If you add tasks with another 10 hours of estimates, the line moves up and starts at 50. If you later remove 20 hours the following day or delete a task, the ideal stays at 50, even though the new estimate is 30 hours.