completeInSprint JQL Function Returns Incorrect Values

The JQL function incompleteInSprint returns issues that are completed in subsequent sprints. For example, if a ticket is not complete when its sprint is finished, it goes in the backlog and it can then be added to the next sprint. If the ticket is completed in this new sprint, it will still show up under the JQL search for issues that were completed in the first sprint when using completeInSprint. Note that it shows up in searches for issues completed in either sprint.