The Initiatives created are getting attached to a project. Is there a way to avoid this? We want initiative to sit in Portfolio until it is assigned to a project. Is this possible?
Initiatives are just JIRA issue and as such need a project to live in. When created in Portfolio they will be part of a Plan scenario (uncommitted changes) and won't show up in JIRA unless committed.
You can have a Project dedicated to initiatives and even have different JIRA workflow with some draft status that can then be filtered out when necessary.
