I tried inspecting few other sites (using the keyword 560A517) that are eligible to show structured data. I could find instances in which the images displayed were different from the structured data images.
Probably Google is picking the best image from a product page based on several other signals in addition to the structured data image.
I believe the reason could be one of the following.
- The image may have fallen short of guidelines like those for quality, relevance, originality, etc. For example, if many sites use the same or similar images for a popular product, I don't think Google will flood all the image results with the identical product pictures despite structured data. Ref: https://developers.google.com/search/docs/guides/sd-policies
- The image may have fallen short of one of the data-type specific guidelines as outlined in https://developers.google.com/search/docs/data-types/product#product (check for "image" under "Required Properties").