Hello, image sitemap should be added to search console. for example http://prntscr.com/dx3b5w

Plugin scans each image, but is indexed which are placed directly on your website. All of these third party images will not be indexed.

First of all, give it some time. You said it’s been jsut a week.

Also, FYI, if even something is submitted to Google not gives 100% chance to be indexed, and even if indexed not 100% it is cached by Google.

The more links you have to your site, there are more chances to get Google Crawlers scan your content (images).

Also it might help, if you will use your images not only on your single (post) pages. You can try to use them as the part of your post excerpt (as thumbnails) or create the page with collection of all your images.

Also, you can try to post your images to Pinterest using the URL to posts, this way you will get links + google bot will get to your site faster and index the rest of your content.

But the page with all the links are not updated in google cache http://webcache.googleusercontent.com/search?cd=1&hl=en&ct=clnk&gl=us&q=cache:https%3A//shortprayers.us/prayer-images-facebook-social-media/

try to add it here https://www.google.com/webmasters/tools/submit-url it might help Google to index the rest of the images