[OmniFocused]

If it's a style/layout thing you changed, you can edit those in preferences but it sounds more like you might have changed the project from parallel to sequential (or vice versa). When you open up that project, click on the arrows right near the task duration - they should either be parallel to each other or intersecting. See if that does it. Or it's possible you changed the parent folder from a single action item to a project? Is the icon the same?