diff --git a/src/SettingsTrait.php b/src/SettingsTrait.php
index 7270b18..eeb1252 100644
--- a/src/SettingsTrait.php
+++ b/src/SettingsTrait.php
@@ -3,23 +3,41 @@
 
 /**
  * Use overloading magic methods for short syntax.
+ * Property accesses are recorded so unparse_custom_settings() can detect
+ * which keys were touched (= natively handled) vs untouched (= potentially custom).
  */
 trait SettingsTrait {
 	protected $settings;
 
+	/**
+	 * Keys accessed via __get / __set / __isset during this object's lifetime.
+	 * Stored as a hash-map (key => true) for O(1) lookup.
+	 *
+	 * @var array<string, true>
+	 */
+	private $accessed_keys = [];
+
 	public function get_settings(): array {
 		return $this->settings;
 	}
 
+	/** Return all keys that were accessed (touched) so far. */
+	public function get_accessed_keys(): array {
+		return $this->accessed_keys;
+	}
+
 	public function __get( string $key ) {
+		$this->accessed_keys[ $key ] = true;
 		return $this->settings[ $key ] ?? null;
 	}
 
 	public function __set( string $key, $value ): void {
+		$this->accessed_keys[ $key ] = true;
 		$this->settings[ $key ] = $value;
 	}
 
 	public function __isset( string $key ): bool {
+		$this->accessed_keys[ $key ] = true;
 		return isset( $this->settings[ $key ] );
 	}
 
diff --git a/src/Unparsers/Base.php b/src/Unparsers/Base.php
index 44fa595..7640598 100644
--- a/src/Unparsers/Base.php
+++ b/src/Unparsers/Base.php
@@ -135,21 +135,44 @@ protected function unparse_conditional_logic() {
 
 		$output = [];
 		foreach ( $conditional_logic as $action => $condition ) {
+			// Fix: chỉ xử lý action đầu tiên ('visible' được ưu tiên hơn 'hidden').
+			// Vòng lặp cũ reset $output['when'] mỗi lần, khiến action trước bị mất.
 			$output['type']     = $action;
 			$output['relation'] = $condition['relation'];
 			$output['when']     = [];
 
 			foreach ( $condition['when'] as $criteria ) {
-				$name = $criteria[0]; // Use field name as key
+				// Fix: dùng uniqid() làm array key thay vì $name.
+				// Nếu cùng field xuất hiện nhiều lần (toán tử khác nhau),
+				// dùng $name làm key khiến rule sau ghi đè rule trước.
+				$uid = uniqid();
+
+				// Fix: convert array value thành CSV string.
+				// Parser/Base.php dùng Arr::from_csv() để chuyển "5,6,7" → [5,6,7].
+				// Chiều ngược lại (Unparser), phải convert [5,6,7] → "5,6,7"
+				// để Builder UI hiển thị đúng — vd: 'in' operator với tax_input.
+				$value = $criteria[2] ?? '';
+				if ( is_array( $value ) ) {
+					$value = implode( ',', $value );
+				}
 
-				$output['when'][ $name ] = [
-					'id'       => $name,
-					'name'     => $name,
+				$output['when'][ $uid ] = [
+					'id'       => $uid,
+					'name'     => $criteria[0],
 					'operator' => $criteria[1],
-					'value'    => $criteria[2],
+					'value'    => $value,
 				];
 			}
+
+			// Chỉ lấy action đầu tiên, thoát vòng lặp.
+			break;
 		}
+
+		// Fix: đánh dấu 'visible' và 'hidden' là đã được xử lý (accessed)
+		// trước khi unset, để unparse_custom_settings() không nhặt chúng lên
+		// và nhét vào custom_settings một cách sai lầm.
+		$this->accessed_keys['visible'] = true;
+		$this->accessed_keys['hidden']  = true;
 		unset( $this->visible, $this->hidden );
 
 		$this->conditional_logic = $output;
diff --git a/src/Unparsers/Field.php b/src/Unparsers/Field.php
index 124b68f..5910033 100644
--- a/src/Unparsers/Field.php
+++ b/src/Unparsers/Field.php
@@ -10,6 +10,7 @@ class Field extends Base {
 
 	private $choice_types = [ 'select', 'radio', 'checkbox_list', 'select_advanced', 'button_group', 'image_select', 'autocomplete' ];
 
+
 	/**
 	 * This is revert of parse method. While parse method converts to the minimal format,
 	 * this method converts back to the original format.
@@ -33,13 +34,17 @@ public function unparse() {
 			->unparse_text_limiter()
 			->unparse_conditional_logic()
 			->unparse_tooltip()
-			->unparse_admin_columns()
-			->ensure_boolean( 'save_field' );
+			->unparse_admin_columns();
 
+		// Field-type handler must run BEFORE unparse_custom_settings() so its
+		// property accesses are tracked and not mis-classified as custom attributes.
 		$func = "unparse_field_{$this->type}";
 		if ( method_exists( $this, $func ) ) {
 			$this->$func();
 		}
+
+		$this->unparse_custom_settings();
+		$this->ensure_boolean( 'save_field' );
 	}
 
 	private function unparse_datalist() {
@@ -140,15 +145,19 @@ private function unparse_field_group() {
 	}
 
 	private function unparse_text_limiter() {
-		if ( ! isset( $this->limit ) ) {
+		// Accept fields that only export limit_type (limit=0 is stripped on export as default).
+		if ( ! isset( $this->limit ) && ! isset( $this->limit_type ) ) {
 			return $this;
 		}
 
 		$this->text_limiter = [
-			'limit'      => $this->limit,
+			'limit'      => $this->limit ?? 0,
 			'limit_type' => $this->limit_type ?? 'word',
 		];
 
+		// Remove flat keys so they are not double-stored alongside text_limiter.
+		unset( $this->settings['limit'], $this->settings['limit_type'] );
+
 		return $this;
 	}
 
@@ -206,6 +215,59 @@ private function unparse_admin_columns() {
 		return $this;
 	}
 
+	/**
+	 * Pure pass-through keys that no unparse_* method ever reads via $this->key.
+	 * They are kept in settings as-is, so they must never be classified as
+	 * user-defined custom attributes.
+	 *
+	 * Every other native key is auto-tracked by SettingsTrait the moment any
+	 * method does $this->key — no need to list them here.
+	 *
+	 * Extend via filter:
+	 *   add_filter( 'mbb_parser_known_field_keys', fn( $k ) => array_merge( $k, [ 'my_key' ] ) );
+	 */
+	private const STRUCTURAL_KEYS = [
+		'type', 'id', '_id', 'name', 'std', 'placeholder',
+		'columns', 'field_name', '_state', 'input_attributes',
+		'multiple', 'fields', 'tab', 'validation',
+		'custom_settings', '_callback', 'options',
+	];
+
+	/**
+	 * Detect unknown top-level keys and move them into the custom_settings
+	 * format `{ uid: { id, key, value } }` that the Builder UI renders in
+	 * the "Custom Settings" tab.
+	 *
+	 * "Known" = auto-tracked by SettingsTrait + STRUCTURAL_KEYS pass-through list.
+	 */
+	private function unparse_custom_settings(): self {
+		$always_native = apply_filters( 'mbb_parser_known_field_keys', self::STRUCTURAL_KEYS );
+		$known         = $this->get_accessed_keys() + array_flip( $always_native );
+		$custom        = $this->custom_settings ?? [];
+
+		foreach ( array_diff_key( $this->settings, $known ) as $key => $value ) {
+			if ( is_resource( $value ) ) {
+				continue;
+			}
+
+			$uid            = uniqid();
+			$custom[ $uid ] = [
+				'id'    => $uid,
+				'key'   => $key,
+				'value' => ( is_array( $value ) || is_object( $value ) )
+					? wp_json_encode( $value )
+					: (string) $value,
+			];
+			unset( $this->settings[ $key ] );
+		}
+
+		if ( ! empty( $custom ) ) {
+			$this->custom_settings = $custom;
+		}
+
+		return $this;
+	}
+
 	public function unparse_default_values() {
 		$this->id  = $this->id ?? uniqid();
 		$this->_id = $this->_id ?? $this->id;