Hi,
Internet Explorer (11 and the other too) is very sensible to HTML errors.
If you got a page with HTML errors and you try to change dynamically some content using javascript, it can delete an entire "invalid" zone.
We see such problem with the product variants, when you change a variant HikaShop replace some elements in the page and if there are some HTML errors, the product image are removed (for example).
In your case, you got some strange HTML in your page
</><!-- EO PRODUCT IMG -->
</><!-- PRODUCT NAME -->
<span class="hikashop_product_name">
<a href="https://www.holz-schnapper.de/index.php/produkt/teelichthalter-herz">
Teelichthalter Herz </a>
</span>
</><!-- EO PRODUCT NAME -->
I don't know why you got some "</>" but I don't think that IE appreciate it (and Firefox marked it as invalid).
Regards,