In obsidian, a document can be viewed in either edit mode or preview mode. In edit mode, you will see basic markdown rendering, but certain things, like code syntax highlighting and embedded files, will only show up in preview mode. Most notably, any images you embed will only be visible in preview mode.
To toggle between preview and edit mode, click the preview button in the title bar. In edit mode, it will appear as a page; in preview mode, a pencil. If you
Cmd/Ctrl- click, the preview will be opened in a Linked pane. You can also toggle Preview Mode by hitting
Cmd/Ctrl-E, but this hotkey can, of course, be changed.