Zend certified PHP/Magento developer

Products showing up in layered navigation after saving them again from admin panel

This is Very weird problem i am into right now, Its a clothing store where i have uploaded 50 products for an example and they are successfully visible in both front and back end.
Now if i apply layered navigation filters on them for I.E BRAND name they are not visible under there brand name. So when i go back in admin panel and just open the product and save it without any changes and refresh the front end it is visible to all. I am not able to understand why i have to save them from back end again to see them in filters list. I am using amasty layered navigation plugin
Please help.