Summary
The $product.QuickView viewpart for aisle templates renders a link in HTML to open quickview's iframe.
<a class="thickbox" alt="Nome do produto" href="http://loja.vtexcommercestable.com.br/quick-view/?idproduto=3672&KeepThis=true&TB_iframe=true">Espiar</a>
When using HTTPS, the destination link protocol stays HTTP, generating a non-HTTPS iframe. Because this falls under mixed content, the action is blocked and iframe doesn't load.
Simulation
All you need is an aisle with a quickview function on a HTTPS page.
Workaround
The only workaround runs into the need to customize the front-end, where a simple Javascript can be implemented, editing the link ("href") of all quickview elements, which would make the URL adopt a HTTPS format, thus allowing iframe to load as expected.