Board configuration for project removed

[Deleted user]

We have a general board that has multiple projects contained in it. We have a project that has issues on this board, but we now want to make this project separate and have it's own board.

I have edited the filter for the board to exclude this project however it still seems to be linked to current sprints. When I try and start the sprint in the new board it updates the existing board with the project not contained in it.

The filter for the existing board does not have the individual project referenced and the new board in the project to be removed has the filter for only this project. Am I missing something here?

Is it possibly because the issues were originally started in a sprint in the main board since removing the filter. I have created a new sprint in the project and started it, but on the board it has the issues in both sprints. When I try to delete the empty sprint on the new board it deletes the current sprint from the main board!

I ideally don't want to create the project again as I have issues already but if I have to do so can someone confirm please.