I have just installed hatch theme on my subdomain.
I created a post to test it. In this post, I uploaded 2 images and I created a gallery with them.
They appeared as thumbails, but there is a grey area at the top of my post.
I read I have to select the gallery and choose one of the image as featured image.
But this option doesn't appear : when I click on each image, I only can delete it.
Thanks for your help !