The template simply display's the posts HTML body as passed by the API, if this html is invalid (e.g. a (image) path is relative instead of absolute, or if a certain script or css file is needed to load some of the html) the html won't be displayed correclty.
Ensure that the post's body, as passed by the API can be loaded as a standalone .html document by making an API call for a post (API request urls can be found in your app's log or be established from the API docs) and extracting the post's body/content from the post (JSON decode first). Now load the body as standalone html and check if it displays correctly.
If it html passed doesn't display correctly, you have now found the cause of why the post isn't displayed correctly in Universal. You can usually fix this by ensuring to use absolute image paths, and disable any plugins or shortcodes that might break your post.
If it does display correctly and the html is valid, it might a bug and we'd be happy to take a look with you at our support center.