There is an issue in Jira Software for Server, which prevents Easy Agile Roadmaps from obtaining the list of projects referenced by your agile board filter.
The bug appears when your board filter excludes a project.
For example, the folowing filter query will not allow us to retrieve the list of projects:
project != KANBAN order by rank
Even more interestingly, if you explicitly specify a project and then exclude another, Jira Software still doesn't return the list of projects:
project = SCRUM and project != KANBAN order by rank
If you run into this issue, you will need to list the projects to include explicitly. i.e.
project in (SCRUM, FOO, BAR) order by rank