The issue is that the “short description” for a variable product is not the “short description” that one would think it would be. Edit the variable product, expand the variations to observe that Facebook for WooCommerce has created a new field located immediately below the variation’s “Description” that is called “Facebook Description”. This will be where you need the “short description” you need in the Facebook details.
How to use that new field to complete the variable product details on Facebook:
1 – Check the box – There is a box to check when you want that description to be transferred to the Facebook details so you will want to check that “Include in Facebook sync” box.
2 – Fill in the “Facebook Description” – put in that field the information you need to see in the Facebook details.
3 – Press the Save changes box and Update the product.
Yes, you will need to make sure the information is completed in every variable product’s variables.
On the Facebook for WooCommerce settings, be sure to have the Product description sync set to “Short description”. Save if you changed it. Sync.