Problem:
Half of the products has featured images, the other half has not.
Solution:
1. Make sure you have marked both options for media attachments on your original product: 'Duplicate uploaded media to translations' and 'Duplicate featured images'. Then try saving and updating your original and translated product.
2. You can use Media translation plugin and in WPML>Settings>Media translations and try to sync images.
- You need to make sure you click the 'Start' button
