Doesn’t work for Frontend uploads

Hi. I was looking for a plugin to automatically create a featured image from the first image in a post. Your plugin works perfectly but I have one problem.

It works when I create a post from my wp-admin (backend), but my website has a frontend image submission system that posts without going through wp-admin, and your plugin doesn’t work (doesn’t create a featured image) when someone posts using my website’s frontend upload. I have to manually update the post in my wp-admin to generate the featured image.

Can you help me figure out a solution? My website uses Frontend Publishing Pro to allow people to upload posts.

Thank you very much.

Also my website is NSFW so I don’t know if I can post it.