Hello @juanchoremo,
I don’t really know what WC Vendors plugin you are using (there is more than 1 WC Vendors plugins). I think most of them create their own templates for Shop page – but I am not sure about that.
If you have upgraded to WC 3.0 (up to 3.0.4) and your WC Vendors plugin has been upgraded for Wc 3.0 compat and your theme also – you could try downloading / upgrading to the latest version of WC Sort and Display to see if it will work together now.
We released Sort and Display maintenance version 1.7.6 with full compat with Wc 3.0.4 and backwards yesterday – that may resolve the compat issues with the WC Vendors plugin that you are using.
This is the new version changelog
1.7.6 – 2017/04/22
* Tweak – Tested for full compatibility with WooCommerce version 3.0.4
* Tweak – Tested for full compatibility with WordPress version 4.7.4
* Tweak – Change call direct to Product properties with new function that are defined on WC v3.0
* Tweak – Called action for save data of plugin after WC data is saved on new WC 3.0 CRUD
* Tweak – Change priority for save_post action so that it is called after WooCommerce save the product data, to get the correct data on WC v3.0
* Tweak – Update query for get products are featured from term instead of product meta on new WC v3.0
* Tweak – Update query to get outofstock products from term instead of product meta on new WC v3.0
* Tweak – Get outofstock from term instead of product meta on new WC v3.0
* Tweak – Update query to get products that are exclude from catalog from term instead of product meta on new WC v3.0