diff --git a/admin-spa/src/hooks/useActiveSection.ts b/admin-spa/src/hooks/useActiveSection.ts
index 5fb6605..b49a545 100644
--- a/admin-spa/src/hooks/useActiveSection.ts
+++ b/admin-spa/src/hooks/useActiveSection.ts
@@ -11,6 +11,12 @@ export function useActiveSection(): { main: MainNode; all: MainNode[] } {
       if (settingsNode) return settingsNode;
     }
     
+    // Special case: /coupons should match marketing section
+    if (pathname === '/coupons' || pathname.startsWith('/coupons/')) {
+      const marketingNode = navTree.find(n => n.key === 'marketing');
+      if (marketingNode) return marketingNode;
+    }
+    
     // Try to find section by matching path prefix
     for (const node of navTree) {
       if (node.path === '/') continue; // Skip dashboard for now
diff --git a/includes/Api/ModulesController.php b/includes/Api/ModulesController.php
index d639ea4..0cca429 100644
--- a/includes/Api/ModulesController.php
+++ b/includes/Api/ModulesController.php
@@ -113,9 +113,25 @@ class ModulesController extends WP_REST_Controller {
         $module_id = $request->get_param('module_id');
         $enabled = $request->get_param('enabled');
         
-        $modules = ModuleRegistry::get_all_modules();
+        if (empty($module_id)) {
+            return new WP_Error(
+                'missing_module_id',
+                __('Module ID is required', 'woonoow'),
+                ['status' => 400]
+            );
+        }
         
-        if (!isset($modules[$module_id])) {
+        // Get all modules to validate module_id
+        $all_modules = ModuleRegistry::get_all_modules();
+        $module_exists = false;
+        foreach ($all_modules as $module) {
+            if ($module['id'] === $module_id) {
+                $module_exists = true;
+                break;
+            }
+        }
+        
+        if (!$module_exists) {
             return new WP_Error(
                 'invalid_module',
                 __('Invalid module ID', 'woonoow'),
@@ -123,28 +139,19 @@ class ModulesController extends WP_REST_Controller {
             );
         }
         
+        // Toggle module
         if ($enabled) {
-            $result = ModuleRegistry::enable($module_id);
+            ModuleRegistry::enable_module($module_id);
         } else {
-            $result = ModuleRegistry::disable($module_id);
+            ModuleRegistry::disable_module($module_id);
         }
         
-        if ($result) {
-            return new WP_REST_Response([
-                'success' => true,
-                'message' => $enabled 
-                    ? __('Module enabled successfully', 'woonoow')
-                    : __('Module disabled successfully', 'woonoow'),
-                'module_id' => $module_id,
-                'enabled' => $enabled,
-            ], 200);
-        }
-        
-        return new WP_Error(
-            'toggle_failed',
-            __('Failed to toggle module', 'woonoow'),
-            ['status' => 500]
-        );
+        // Return success response
+        return rest_ensure_response([
+            'success' => true,
+            'module_id' => $module_id,
+            'enabled' => $enabled,
+        ]);
     }
     
     /**
diff --git a/includes/Compat/NavigationRegistry.php b/includes/Compat/NavigationRegistry.php
index 6f1782b..43682d7 100644
--- a/includes/Compat/NavigationRegistry.php
+++ b/includes/Compat/NavigationRegistry.php
@@ -260,10 +260,12 @@ class NavigationRegistry {
     }
     
     /**
-     * Flush the navigation cache
+     * Flush navigation cache
      */
     public static function flush() {
         delete_option(self::NAV_OPTION);
+        // Rebuild immediately after flush
+        self::build_nav_tree();
     }
     
     /**