On the Team Board or Work Views pages, the values in the columns and on the Cumulative Flow Chart are different.
The Cumulative Flow chart was designed only to show items that have moved into a column in the last 30 days. Any items that were moved more than 30 days ago will not be included in the Cumulative Flow Chart.
You have 5 items in a column called Last
2 of the User Stories were moved to the Last column 3 months ago, and 3 were moved there 2 weeks ago.
Therefore, 5 items show in Last column on the Team Board, but only 3 show in the Cumulative Flow chart under Last.