Looks like the REST APIs for /rest/agile/1.0/board?&type=scrum&projectKeyOrId=PROJECT_KEY
Changed subtly where it now relies on the JQL's project keys rather than the Project Shares. So if you had a Scrum filter that doesn't specify a project key, it won't show up on the project specific queries.
This means that:
If you have a board with a JQL "priority > Medium" shared with project DEV
Project scoped rule for project DEV
You try to pick a board or an Epic in any of the actions, it will show no Epics / boards in the drop down. You should still be able to pick a board from the global list as a fall back
We should fall back, so that if a call to get boards / epics for a project comes back empty, fetch it again with no project param (so you can do global Epic / Board searches)