Blog image width problem

Hi, 

I am using the Native template in 7.0. I have a "News" page which is set up using the blog demo page in the template (it is currently not enabled). When I add an image block at the beginning of a post, it initially conforms to the set blog content width (600px) but it then reverts to the set site width (1280px) after saving and re-loading the page. This results in a massive image stacked over thin columns of text. The post title also moves from above the image to below. Does anyone know why this is happening? 

I've attached screenshots showing 1) the image while editing the post, 2) the image after saving the post, and 3) and 4) the image after refreshing the page. The images are an image block with the inline setting.

Thanks in advance.

Hi,

Can you share link to a blog post? We can check problem easier

Here's the link: https://www.killackeyillustration.com/news. I've enabled the page for now so you can see it but it's not currently linked to my navigation. The top post exhibits the issue I'm asking about. I've discovered that is a place a text block above the first image block it stops the image from expanding (see previous posts on page). Not an ideal solution but a work around I can use if there's nothing else. 

Thanks!

If you need to increase post width, you try adding this to Design > Custom CSS or Website > Website Tools > Custom CSS

/* blog post width */
.collection-type-blog article .post {
    max-width: 1200px !important;
}