No posts displayed in the calendar for non-admins when Permissions is installed

[andergmartins]

Expected Behavior

As a logged in contributor, I expect to see all the posts in the calendar.

Current Behavior

If I'm not an admin (contributor, for example), I can see the posts in the calendar. But once I install Permissions, the calendar appears empty.

Steps to Reproduce (for bugs)

1. Install PublishPress;
2. Create a contributor user;
3. Create posts and check if they are visible in the calendar;
4. Log in as the contributor, and check the calendar again, you should still see those posts;
5. Log in as admin and install Permissions;
6. Log back as contributor and check the calendar again, it will be empty, or missing posts;

Related support ticket https://secure.helpscout.net/conversation/1630909915/151463?folderId=2557470