Photos not appearing from imported blog on the app only

Hi, I am totally new to doing anything other than subscribing on Substack. I thought I'd give Substack a try and imported some blog posts from a Squarespace website, just to have some posts and see what it does, looks like, etc.

When I look at my posts on a browser, everything looks fine. Photos imported along with the text of the original blog posts.

But when i look at the Substack app, only one blog post appears to have photos that also imported. There are just blank boxes where the photos should be.

What am i doing wrong?

Thank you!