Description:
Warning: Provided variations without linking any images to variations.
This means you might not have properly linked images to your product's variants. Your listings will still be posted to Etsy however, the settings for pictures might not be how you want them.
Solution:
This can be caused by using option#_value as your image_for_option information. Use option#_name data instead.
This could also be caused by not providing images in the Shop Uploader template.