We have a large JIRA project. There is an active sprint with lots of tasks in it.
A colleague and I have created some tasks, and these all have the "Scrum Team" field set to the name of our sub-team.
Looking at the backlog page of our board, we can see our tasks (and only our tasks, since the filter query includes a filter on the "Scrum Team" field).
However, there is no sprint visible in the backlog page, and when I right-click on an issue in order to add it to the sprint, there is no such option on the dropdown menu.