Hi,
Sorry for the late response.
The plugin "Woocommerce Products Layout" just help you build a custom shop page. (Not set the detail Shop page).
If you set Product Masonry Page as the detail Shop Page -> Woocommerce will understand that: the shortcode "Product Masonry" is the description of the default Shop page. -> The detail Shop Page will display concurrent content of shop detail and shortcode "Product Masonry".
To better understand you can create a new page and add some the text. Later you assign to the detail Shop Page. -> you go to frontend and load Shop detail -> The text and product shop will display concurrent content.
Best regards.