Posting in the Magento forums has been disabled pending the implementation of a new and improved forum solution which should better serve the community.
For new questions please post at magento.stackexchange.com, the community-run support site for the Magento community. We will be providing updates on the new forum solution soon. For questions or concerns please email firstname.lastname@example.org.
Just solved this. :-D
Go to Cache Management -> Catalog -> Layered Navigation Indices -> click on Refresh now.
Now, if you get error “Maximum Execution Time exceed”, increase the php setting “max_execution_time” to 300 and it should be enough to run this process. My site has more than 800 products and 5 custom attributes to be filtered.