The widget code is installed on your theme and you've added accessories to your products but the app isn't displaying or some accessories aren't showing?
Check the accessory product
Your accessory product is most likely out of stock or not available to the online store.
Check your product by viewing it in the product tab of your store:
The app will not display an accessory if it can't be purchased. If no assigned accessories are available or in stock then the app will not display at all. If a variant is sold out, then that specific variant will not show in the options: