Hello Rowena,
Please let checked your screenshot again:
In normal LayerSlider loading without any PageSpeed installed, the plugin will load these files:
/wp-content/plugins/LayerSlider/assets/static/layerslider/js/layerslider.utils.js?ver=6.11.2
/wp-content/plugins/LayerSlider/assets/static/layerslider/js/layerslider.kreaturamedia.jquery.js
/wp-content/plugins/LayerSlider/assets/static/layerslider/js/layerslider.transitions.js?ver=6.11.2
If you look closely at your screenshot, PageSpeed minified the LayerSlider resources and generated totally new files. Kindly temporarily disable PageSpeed so that you can compare the files that are loaded on your page.
Kindly let us know how it goes.