Sometimes when you click on Add to Cart button for an item on My Wishlist page, it displays a modal (popup) stating Please choose a variant before adding this item to cart.
This behavior is perfectly normal and is intended to prevent wrong variants from getting added to the Shopping Cart.
This happens for those products matching the following criteria
1. The Product Item has not been added to Wishlist from Single Product page (i.e. added from Collection, Search Result, Home Page etc.)
2. The Product item has multiple variants.
When both of the above conditions are satisfied, the App displays a modal stating “Please choose a variant before adding this item to cart” or a similar message. On this modal, the user is presented with an option of “Choose Variant”, upon clicking which he is redirected to individual product page where he can select the desired variant and add the item to Shopping Cart.