We have set up our Jira as follows: 1 project (we call it PLAN) that houses all epics. Each of our product teams have their own projects (probably upwards of 20 different projects). Each project team houses their user stories that get associated to one of the epics in the PLAN project. When a story completes, the release gets associated to a story. There could be several stories from the same project associated with the epic in PLAN or stories from several different projects associated with the epic in PLAN. It's possible that some or none of the stories will have a release on it depending on if the release on the epic speaks for everything associated with it.
We are struggling with how to manage and report the releases with the set up we have. We have looked into advanced roadmaps, but not sure that is a solution for us or not. Any ideas are welcoming.