How to interpret CFD if the tasks keeps accumulating?

[Krishnan Mudaliar]

Be it Sprints or Kanban, the CFD seems skewed, in that, over time, ALL tasks in DONE status since the beginning show up in the report, even if I have a shorter date range selected. Is that the intended behavior?

Attaching a screenshot of how it looks for me:

image2016-9-18 16:17:13.png

If this is not supposed to be so, I have a strong feeling that my project settings has a quirk as the reason for this. One thing I know for sure is that my project has a custom Workflow without any of the default Close/Reopen statuses or transitions. Could that be the reason?

[Krishnan Mudaliar]

I see that the screenshot I added was not of a shorter date range, so here is one more:

image2016-9-18 16:44:18.png

(Please don't mind the changes in Legend at top-left — diagrams from different boards)