Update Image of Product Variant

How does one update a variant image?

The documentation shows how to create a new product with images by populating images_attribute (POST).

Following this example, I have tried updating (PUT) images_attribute… (I have tried to both pass a product_id and display_order value as part of the update) but this does not seem to work. For example:


I have also tried defining the main_image property inside the associated product variant as part of the update…


At this point, I am not sure what else to try or what I am doing wrong…?