I'e had a recurring problem with the Membership plugin, where members are getting logged out of the membership side of our website. This is happening both for members and Admin.
The Wordpress black bar disappears when a member visits our member pages. However, refreshing the page via the browser logs them back in and the Wordpress black bar reappears.
This happened infrequently at first, but now it happens all the time.
The problem may lie in that I have member pages and Visitor pages with the same URLs. Members see different content than visitors when viewing a page with the same URL.