Sprint cannot be completed as there are incomplete subtasks on the following issues. Future sprint

[Luke Higgins]

This error is showing but the task is says the issue is with is in a future sprint.  I can't remedy. 

[Luke Higgins]

I created a 'report' showing ticket not Done and still in the sprint. 

Only one ticket showed, the Task with the subtask that was having the issue.  The Task listed showed the parent task but the link to the record showed and took me to the subtask.  Buggy. 

I went to the subtask, which inherited the parent's future sprint, marked it Done, closed my current sprint and then marked the subtask with the old status. 

Fixed the issue but this is clearly a bug.