Mini Cart block: Add-to-Cart behaviour attribute is ignored when adding the first product

[Aljullu]

For some reason, it looks like the 'Add-toCart behavior' is not being applied when adding the first product to the Cart.

To reproduce

1. Go to Appearance > Editor and add the Mini Cart block to the header of your store.
2. Make sure the Open cart in a drawer option is disabled:
   
3. Go to the frontend and add a product to your cart from the Shop page.
4. Notice the drawer opens.

Expected behavior

If the Open cart in a drawer option is disabled, the drawer shouldn't open in any case.