Check all field instances to see if they're dirty/modified/have errors

Resolves craftcms/ckeditor#391

Author: brandonkelly

CHANGELOG.md

@@ -1,5 +1,9 @@
 # Release Notes for Craft CMS 5
 
+## Unreleased
+
+- Fixed a bug where changes to multi-instance CKEditor fields weren’t persisting, if the first instance in the field layout hadn’t been modified. ([craftcms/ckeditor#391](https://github.com/craftcms/ckeditor/pull/391))
+
 ## 5.6.15 - 2025-04-04
 
 - Fixed an error that could occur when clearing control panel resources, if the `resourceBasePath` setting was set to a nonexistent folder path. ([#17021](https://github.com/craftcms/cms/pull/17021))

src/elements/NestedElementManager.php

@@ -28,6 +28,7 @@
 use craft\helpers\Html;
 use craft\helpers\StringHelper;
 use craft\models\Site;
+use Generator;
 use Throwable;
 use yii\base\Component;
 use yii\base\InvalidConfigException;
@@ -683,7 +684,14 @@ private function isDirty(ElementInterface $owner): bool
             return $owner->isAttributeDirty($this->attribute);
         }
 
-        return $owner->isFieldDirty($this->field->handle);
+        foreach ($this->fieldInstances($owner) as $instance) {
+            /** @var FieldInterface $instance */
+            if ($owner->isFieldDirty($instance->handle)) {
+                return true;
+            }
+        }
+
+        return false;
     }
 
     private function isModified(ElementInterface $owner, bool $anySite = false): bool
@@ -692,13 +700,49 @@ private function isModified(ElementInterface $owner, bool $anySite = false): boo
             return $owner->isAttributeModified($this->attribute);
         }
 
-        return $owner->isFieldModified($this->field->handle, $anySite);
+        foreach ($this->fieldInstances($owner) as $instance) {
+            /** @var FieldInterface $instance */
+            if ($owner->isFieldModified($instance->handle, $anySite)) {
+                return true;
+            }
+        }
+
+        return false;
     }
 
     private function hasErrors(ElementInterface $owner): bool
     {
-        $attribute = $this->attribute ?? $this->field->handle;
-        return $owner->hasErrors("$attribute.*");
+        if (isset($this->attribute)) {
+            return $owner->hasErrors("$this->attribute.*");
+        }
+
+        foreach ($this->fieldInstances($owner) as $instance) {
+            /** @var FieldInterface $instance */
+            if ($owner->hasErrors("$instance->handle.*")) {
+                return true;
+            }
+        }
+
+        return false;
+    }
+
+    private function fieldInstances(ElementInterface $owner): Generator
+    {
+        if (!isset($this->field)) {
+            return;
+        }
+
+        if (!$this->field::isMultiInstance()) {
+            yield $this->field;
+            return;
+        }
+
+        $customFields = $owner->getFieldLayout()?->getCustomFields() ?? [];
+        foreach ($customFields as $field) {
+            if ($field->id === $this->field->id) {
+                yield $field;
+            }
+        }
     }
 
     private function saveNestedElements(ElementInterface $owner): void