First let me start by saying that I will not update to the new version of joomla or virtuemart, every time I do that I break the template (or the template breaks me) I also understand that you are not here to offer support for commercial templates, I just hope this is a common problem that is fixable in the back end or with minor code adjustments.
RIght now I have Joomla 3.5.1 and Virtuemart 3.0.14
Whenever I hover over a product thumbnail in category view the thumbnail minimizes, you can check it on my site www.underwater-merch.eu
It might just be the fact that I suck at this, but I do believe this template is made by Satan himself and is here only to make me suffer. And no, I can't change the template.
You looked with Firebug? http://forum.virtuemart.net/index.php?topic=116620.0
You need to correct the css issues identified:
.product-image-area .hover-area {
background: rgba(0, 0, 0, 0) url("../images/product_overlay.png") repeat scroll 0 0;
display: none; <--------------------
height: 100%;
left: 0;
overflow: hidden;
padding-top: 80px;
position: absolute;
text-align: center;
top: 0;
width: 100%;
z-index: 10; <-------------------
}