Index: src/bp-activity/classes/class-bp-activity-activity.php
===================================================================
--- src/bp-activity/classes/class-bp-activity-activity.php
+++ src/bp-activity/classes/class-bp-activity-activity.php
@@ -613,6 +613,18 @@
 				$activities = $wpdb->get_results( apply_filters( 'bp_activity_get_user_join_filter', "{$select_sql} {$from_sql} {$join_sql} {$where_sql} ORDER BY a.date_recorded {$sort}, a.id {$sort}", $select_sql, $from_sql, $where_sql, $sort, $pag_sql ) );
 			}
 
+			// Integer casting for legacy activity query.
+			foreach ( (array) $activities as $i => $ac ) {
+				$activities[ $i ]->id                = (int) $ac->id;
+				$activities[ $i ]->item_id           = (int) $ac->item_id;
+				$activities[ $i ]->secondary_item_id = (int) $ac->secondary_item_id;
+				$activities[ $i ]->user_id           = (int) $ac->user_id;
+				$activities[ $i ]->hide_sitewide     = (int) $ac->hide_sitewide;
+				$activities[ $i ]->mptt_left         = (int) $ac->mptt_left;
+				$activities[ $i ]->mptt_right        = (int) $ac->mptt_right;
+				$activities[ $i ]->is_spam           = (int) $ac->is_spam;
+			}
+
 		} else {
 			// Query first for activity IDs.
 			$activity_ids_sql = "{$select_sql} {$from_sql} {$join_sql} {$where_sql} ORDER BY a.date_recorded {$sort}, a.id {$sort}";