I’ve never even heard of that plugin.
Also, The ‘Preview’ will almost never look like what you seen on the front-end. When you view the front-end of a WordPress site, all the Front-End CSS style loads for whatever WP Theme you are using. In the WordPress Dashboard, none of that Front-End CSS style exists. The ‘Preview’ I put in to give an idea of of how it will look on the front-end – I sometimes wonder if I should remove this feature, but maybe people use it…
WordPress themes can and do sometimes have a big effect on how Slide Anything displays, especially WP themes that incorporate Owl Carousel as well (which is what I built SA on). Sometimes testing in another theme (e.g. 2017 theme) can highlight whether this is in fact the case.