I am trying to call an update layout handle in a product design custom layout update by inserting this code
<update handle="my_handle"/>
but nothing appears, if I put the content of that handle it shows up correctly or if I put this code in my xml
<default>
<update handle="my_handle"/>
</default>
it works fine so my handle should work.
Is there something that loads those handles before calling the product custom design update?