I successfully created a multi project board by first creating a filter for the first two projects and then creating a board using that filter. It worked great and all the issues for those two projects showed up on my multi-project board. However when I attempt to add a third project, the issues for the added project are not showing up on the board. From the Configure Board page, I edited the filter to include the new project, and the search seems to be successful as both the existing and new projects show up on the Configure page. However when you return to the Muti-project board only the issues from the original projects are displayed.