We are using multiple boards within the same project to represent each team. We have an additional board in the project for our product team, which is where our epics live since they span multiple sprints. I have stories from the epic assigned to multiple teams/boards. However, when I run the epic burndown, I cannot see issues from all of the boards. How can I see an epic burndown when multiple teams (boards) are working on the same epic? This is within one project.
What problem are you trying to solve with that type of Epic Burn chart?
I am wondering as I believe the built-in epic burn chart uses story points not item counts. And story points are often distinct units of measure for each delivery team. So adding values across teams may not produce your intended results.
If you were trying to see current "status" for an epic, you could use a two-dimensional filter gadget on a dashboard by Epic Link and Status; that would show total counts.
If instead you needed to see information over time, perhaps a marketplace add-on with improved reporting gadgets would help.