I am not surprised it works like that. Floating images is a very crude method. It pretty much does what is asked. And that’s why I never float anything deliberately, whether it’s blocks, or articles or forum posts.
It also doesn’t play well with the responsiveness of the page, because you force a width that might work in one window size but not another.
For a proper view of that layout, you would currently need custom HTML and IPS’ column or grid CSS. That can also deal with the responsiveness.