Delete epic causes backlog and sprint items to disappear

From my agile planning board, I create an epic and assign tasks to it. I then decide that I do not need that epic, so I delete it. The contents of all sprints and backlog is cleared, and there is no way to get them back unless I recreate the epic again.

After further investigation the problem is that if I click on the epic in the agile board, and then choose to open in Jira, then delete, the agile board 'remembers' that I had selected the epic, and still tries to filter by it. If I only have one epic there is no other epic to choose, therefore the filtering is incorrect.