This feature is available in all editions.
The Remaining Estimate in Release Forecasting indicates the open estimate at the beginning of the forecast period, and may include estimate for worktems that have been closed since that date.
The Estimate Trend report shows the current open estimate.
How to manually reconcile
If you wish, you can manually reconcile the numbers by finding the workitems that are included in the Release Forecasting Remaining Estimate but excluded from the current estimate. First, customize your backlog view as follows:
Customize the backlog grid to show Change Date
Sort the backlog in descending order by Change Date.
Select the Show Closed Items filter. Your view should look like this:
Next, determine the end date of the last historical period on the Release Forecasting chart.
Now locate the items with a change date between the period end date and today. Sum the estimates for those items. This number is the total estimate of items that have been closed since the beginning of the forecast period.
Finally, add the closed estimate you just calculated to your current estimate from the Estimate Trend report. This number should match the Remaining Estimate.
Alternatively, you can subtract the closed estimate from the Remaining Estimate, which should in turn match the current estimate from the Estimate Trend report.