Hi,
Screenshots unfortunately don't tell anything.
Are you working on a live server? Can you please share me URLs from website where this "white pages" occurs?
For instance, i tried to simulate the same scenario on the Live Demo of Asymmetric but i didn't notice any problem.
1- Open the Live Demo of Asymmetric:
demo.flexiblewebdesign.com/asymmetric/index.php
2- Search this keyword: "Sample", which will generate this url:
demo.flexiblewebdesign.com/asymmetric/index.php?keyword=sample&limitstart=0&option=com_virtuemart&view=category&lang=en
3- On the search result page, filter products by manufacturer: "Prada", which will generate this url:
demo.flexiblewebdesign.com/asymmetric/index.php?option=com_virtuemart&view=category&limitstart=0&lang=en&language=en-GB&keyword=sample&manage=0&virtuemart_manufacturer_id=2
4- You will get 2 products (keyword: "sample", manufacturer: "prada")
Regards