This happens possibly because both your blog and the mobile version have a dynamic template. InLinkz cannot pick the images from the dynamic template.
One solution is to change the mobile version to a non dynamic template (inlinkz checks both the desktop and the mobile version)
See more here: https://inlinkz.freshdesk.com/solution/articles/5000565158-i-enter-my-blog-but-when-the-page-to-select-the-image-comes-up-no-images-are-shown
If this is not possible or you do not want it, you must check the checkbox to submit the link and it will be shown only after
the blog owner has accepted it.