When I complete a sprint and start a new one, what typically happens is that all "non-done" tasks become part of the new sprint, and all "done" tasks from the previous sprint disappear.
Last week, however, when I completed a sprint and started a new one, the "done" tasks from the previous sprint remained in the new sprint. They are still marked as done. They just shouldn't be there. Aside from manually deleting them, I'm not sure what to do. I'm mostly curious to know why this happened and how I can ensure it doesn't happen in future sprints.
Any help would be appreciated!