This BETA option enables stock filter support for variable products. Stock availabilities will be filtered based on variations’ stock status, in combination with other active filters.
The Stock filter variations support option may slow down the product lists display on sites with slow servers and/or large amounts of products. It may NOT work properly in shops with more that 10000 products.
This option supports the WooCommerce > Settings > Products > Inventory > Out of stock visibility setting. Whenever the Hide out of stock items from the catalog option is checked, the products with out of stock status will not be displayed in the filtered product lists.
The Out of stock filter on the other hand, will display out of stock products even with Out of stock visibility enabled.
Starting with version 1.5.1 of the filters, the variable products’ stock status support code has been rewritten to take advantage of the new WooCommerce lookup tables. This enhanced version of the Stock filter variations support option gets auto-activated on sites that have the Enable table usage enabled on the WooCommerce > Settings > Products > Advanced admin screen.
If you notice that stock status of your variable products gets updated with large delays, try enabling the WooCommerce > Settings > Products > Advanced > Direct updates option.