Steps to reproduce bug:

1. Create data object class Test, enable inheritance, add an image gallery field named images
2. Create Test object /parent
3. Create Test object /parent/child (so that it inherits data from /parent)
4. Assign an image to the image gallery field of /parent, add a hotspot, save

Expected behaviour:
Image gallery data gets inherited to the child object, thus in database table object_query_Test the column images__hotspots there is the same data for /parent and /parent/child

Actual behaviour:
Column images__hotspots only gets filled for /parent but not for /parent/child.
After saving the child, images__hotspots is the same for both objects.

Cause:
The place which is responsible for writing inherited data for the child objects to the query tables is

Here getIdsToUpdateForValuefields() does not recognize the child column to be empty. There are multiple quirks here:

1. In

   pimcore/models/DataObject/Concrete/Dao/InheritanceHelper.php

   Lines 524 to 525 in 514e9ce

   	$value = $currentNode['values'][$fieldname] ?? null;
   	if ($this->fieldDefinitions[$fieldname]->isEmpty($value)) {

   
   $fieldname is images__hotspots and so value is only the content of this column, not all columns which belong to image gallery data. But $this->fieldDefinitions[$fieldname] is a Pimcore\Model\DataObject\ClassDefinition\Data\ImageGallery object. So the actual $value does not match what ImageGallery::isEmpty() usually expects to get (a Pimcore\Model\DataObject\Data\ImageGallery object or null).
2. $value is the string "a:0:{}" because when saving an image gallery without hotspots, an empty array gets serialized in

   pimcore/models/DataObject/ClassDefinition/Data/ImageGallery.php

   Line 118 in 514e9ce

   $this->getName() . '__hotspots' => Serialize::serialize($hotspots),

   and stored in database.

So one way to solve the problem would be to add a check for $data === "a:0:{}" in

For this reason I decided for a different approach: When saving an image gallery without hotspots, we store null in the database. This way the ImageGallery::isEmpty() will return true and thus the image gallery data in the query table gets updated when the parent gets saved.