Due to the function-based organization of my org we have opted to use a centralized shared epic model where teams share an epic (based on component tagging) and contribute their own local team stories/tasks/bugs etc) to an epic shared across teams. We are leveraging Structure to create team roadmaps based on shared epics with their team component tagged.
When a team tries to access the structure from a board from their jira project via left nav , you default a filter to project. = <current project>, which essentially wipes out the Structure rendering it useless. We have found a workaround for now of extending stories and then manually dragging the default filter to the right of the extension.
It is annoying though that you don't allow me to change or remove the default filter. I understand why it is there - but this use case doesn't fit into you application model.