Index: src/bp-core/bp-core-buddybar.php
===================================================================
--- src/bp-core/bp-core-buddybar.php
+++ src/bp-core/bp-core-buddybar.php
@@ -342,6 +342,19 @@
 		// No subnav item has been requested in the URL, so set a new nav default.
 		if ( empty( $unfiltered_action ) ) {
 			if ( ! bp_is_current_action( $r['subnav_slug'] ) ) {
+				/*
+				 * If the screen function isn't available, attempt to find it.
+				 *
+				 * This is due to our conditional-loading code since v3.0.0.
+				 */
+				if ( ! is_callable( $r['screen_function'] ) ) {
+					$file = $bp->{$parent_nav->slug}->path . 'bp-' . $parent_nav->slug . '/screens/' . $r['subnav_slug'] . '.php';
+					// Found the file, so require it.
+					if ( file_exists( $file ) ) {
+						require_once $file;
+					}
+				}
+
 				if ( is_callable( $r['screen_function'] ) ) {
 					add_action( 'bp_screens', $r['screen_function'], 3 );
 				}