Issues typically represent a problem that needs to be fixed (whereas ideas represent suggestions). They can describe errors or disadvantages associated with the ongoing work in the Circle.
An issue is the same as a story in many ways: it has many of the same properties and can be planned and handled like a story. It can even be converted into a story.
However, issues can also be set as implemented by a story, when solving the issue is actual a part of that story. The state of the issue will then follow the state of the story.
Issues are placed along with ideas in a separate part of the Storymap Tree and can be categorized in folders.