I've uploaded product images with the REST API.
They look fine on category / list pages, and in the admin interface.
However, on the product pages I just get the missing/placeholder image.
If I download the exact file from the admin interface, and the re-upload it(as a second product image) in the admin web ui, then it will show up on the product page.
I guess I'm going to try closely comparing what they look like in REST get responses, but nothing obvious visible in admin web ui.
It was the 'disabled' media item attribute - which I see no ui for in the admin area.
Yes you need to pass false value in disabled media parameters , like 'disabled' => false
And in ui option is there when you click on product image from admin - Popup will open over there at the bottom there is checkbox option hide from product page which does the same.
Hope it helps to you !!