show_block_custom_main.php override don't work with characteristics

-- url of the page with the problem -- : joomla-webshops.nl/hikashop/products/product/2-stilettos
-- HikaShop version -- : 4.4.1

Hi Guys,

There is a problem with show_block_custom_main.php in combination with characteristic selection.

See Url of the page: joomla-webshops.nl/hikashop/products/product/2-stilettos

I created an override for show_block_custom_main.php.
The only thing i changed in this override is:
<h4><?php echo JText::_('SPECIFICATIONS');?></h4>
to:
<h2><?php echo JText::_('SPECIFICATIONS');?></h2>

When you look at the page on first load, it looks good.
When you select color and shoesize the override of show_block_custom_main.php switches back to the original (H4 title)
In this case (test-website) it's not a great problem, but for my client on his live-site i created a completely different styling which really looks odd when you select the characteristic.

Can you fix this? Or tell me what to do to always show the override.
Thanks in advance.
Jeroen

thanks this works!