Different sprints for different Agile boards, doesn't seem to be working?

Jace Proctor

My JIRA is split into two different projects, and each one has its own Agile board.  Because they sometimes work on different schedules and have different organizational needs, it's important that each board/project has its own sprints.  

This was previously working before the recent changes to Agile, but now it seems that sprints are shared across boards/projects.  Oddly it seems that SOME are shared, and SOME aren't. 

Why is this, and can someone link me to a more thorough explanation of how this works?  

Jobin Kuruvilla [Adaptavist]

A Sprint appears in a board if the board shares some of the data with another board on which the Sprint was originally created. When I say the data is shared, it could be because the filter of the board pulls in data from the other project. Is that the case here?