We created two new sprints on Monday, including a new set of issues. We noticed that all of the other sprints have disappeared. All of the issues still exist, but they are all associated with a newly created sprint that we did not create.
When we pick one of the issues and view the Details...select Sprint...uncheck "Only show sprints this project, the "recent sprints" appear.
[image available but removed because of "character limit]
However, if we leave it checked, only the two new sprints appear in the list.
[image available but removed because of "character limit]
I do not know if this is relevant, but we were switched to a trial standard plan (this was NOT based on our explicit action). At some point early in the week, the trial ended.