Lazy Load for Joomla should not be used with the Virtuemart 2 component. Did try it out and the result was, that the product detail page does not show images. Using google mod_pagespeed and activating there the lazy image load has the same result: no images. So it it not a bug in the Lazy Load for Joomla if it does not work with virtuemart. Lazy Loading images cannot be used with Virtuemart!