BuddyPress.org

BuddyPress member themes should be located under /wp-content/bp-themes/.

Please note, just recently this changed. Before, the BP member themes were installed under /wp-content/member-themes/.

Of course, it depends on which version of BP you’re running, but you should check to see if you have a /bp-themes/ or a /member-themes/ folder under /wp-content/. Then, make sure that you have an actual member-based theme installed in that folder.