Hi,
Recently in HikaShop, we've added the trigger of the events onPrepareModuleList, onAfterModuleList and onAfterCleanModuleList on the modules displayed in the "modules under the product page.
So I suppose it could be the template implementing these triggers in a plugin to add its HTML around the modules for some reason.
It's done by the lines:
$app->triggerEvent('onPrepareModuleList', array(&$this->modules));
$app->triggerEvent('onAfterModuleList', array(&$this->modules));
$app->triggerEvent('onAfterCleanModuleList', array(&$this->modules));
in the file components/com_hikashop/views/product/view.html.php
We've added these so that extensions, like Advanced Modules Manager, can process the modules.
So try deleting these lines and see if that helps. I suppose it will, and in that case, you can talk to the Yootheme forum and ask them what's going on with these events and Yootheme.