diff --git a/ai/provider/openai/classes/aimodel/dalle3.php b/ai/provider/openai/classes/aimodel/dalle3.php
index f35124448df..93d5d918e6d 100644
--- a/ai/provider/openai/classes/aimodel/dalle3.php
+++ b/ai/provider/openai/classes/aimodel/dalle3.php
@@ -43,7 +43,7 @@ class dalle3 extends base implements openai_base {
     }
 
     #[\Override]
-    public function model_type(): int {
-        return self::MODEL_TYPE_IMAGE;
+    public function model_type(): array {
+        return [self::MODEL_TYPE_IMAGE];
     }
 }
diff --git a/ai/provider/openai/classes/aimodel/gpt4o.php b/ai/provider/openai/classes/aimodel/gpt4o.php
index fceb5118264..07e89eef1ad 100644
--- a/ai/provider/openai/classes/aimodel/gpt4o.php
+++ b/ai/provider/openai/classes/aimodel/gpt4o.php
@@ -81,7 +81,7 @@ class gpt4o extends base implements openai_base {
     }
 
     #[\Override]
-    public function model_type(): int {
-        return self::MODEL_TYPE_TEXT;
+    public function model_type(): array {
+        return [self::MODEL_TYPE_TEXT];
     }
 }
diff --git a/ai/provider/openai/classes/aimodel/o1.php b/ai/provider/openai/classes/aimodel/o1.php
index 34560e7cdfa..3a5c2bdc6d6 100644
--- a/ai/provider/openai/classes/aimodel/o1.php
+++ b/ai/provider/openai/classes/aimodel/o1.php
@@ -41,7 +41,7 @@ class o1 extends gpt4o {
     }
 
     #[\Override]
-    public function model_type(): int {
-        return self::MODEL_TYPE_TEXT;
+    public function model_type(): array {
+        return [self::MODEL_TYPE_TEXT];
     }
 }
diff --git a/ai/provider/openai/classes/aimodel/openai_base.php b/ai/provider/openai/classes/aimodel/openai_base.php
index e81464a9d4a..9535d4ddddd 100644
--- a/ai/provider/openai/classes/aimodel/openai_base.php
+++ b/ai/provider/openai/classes/aimodel/openai_base.php
@@ -31,9 +31,9 @@ interface openai_base {
     public const MODEL_TYPE_IMAGE = 2;
 
     /**
-     * Get model type.
+     * Get model types.
      *
-     * @return int Model type.
+     * @return array List of model types.
      */
-    public function model_type(): int;
+    public function model_type(): array;
 }
diff --git a/ai/provider/openai/classes/form/action_form.php b/ai/provider/openai/classes/form/action_form.php
index fdc1ab14b84..bbd1260c023 100644
--- a/ai/provider/openai/classes/form/action_form.php
+++ b/ai/provider/openai/classes/form/action_form.php
@@ -140,6 +140,7 @@ class action_form extends action_settings_form {
         global $PAGE;
         $PAGE->requires->js_call_amd('aiprovider_openai/modelchooser', 'init');
         $mform = $this->_form;
+        $actionname = $this->actionname;
 
         // Action model to use.
         $mform->addElement(
@@ -155,13 +156,15 @@ class action_form extends action_settings_form {
                 (!array_key_exists($this->actionconfig['model'], $this->get_model_list($modeltype)) ||
                 !empty($this->actionconfig['modelextraparams']))) {
             $defaultmodel = 'custom';
+        } else if (empty($this->actionconfig['model'])) {
+            $defaultmodel = ($actionname === 'generate_image') ? 'dall-e-3' : 'gpt-4o';
         } else {
-            $defaultmodel = $this->actionconfig['model'] ?? 'gpt-4o';
+            $defaultmodel = $this->actionconfig['model'];
         }
         $mform->setDefault('modeltemplate', $defaultmodel);
         $mform->addHelpButton('modeltemplate', "action:{$this->actionname}:model", 'aiprovider_openai');
 
-        $mform->addElement('hidden', 'model', $this->actionconfig['model'] ?? 'gpt-4o');
+        $mform->addElement('hidden', 'model', $defaultmodel);
         $mform->setType('model', PARAM_TEXT);
 
         $mform->addElement('text', 'custommodel', get_string('custom_model_name', 'aiprovider_openai'));
@@ -189,7 +192,7 @@ class action_form extends action_settings_form {
         $models['custom'] = get_string('custom', 'core_form');
         foreach (helper::get_model_classes() as $class) {
             $model = new $class();
-            if ($model->model_type() == $modeltype) {
+            if (in_array($modeltype, $model->model_type())) {
                 $models[$model->get_model_name()] = $model->get_model_display_name();
             }
         }