I can see you are using the Autoptimize plugin which can be overly zealous when it comes to minimising javascript.
Would you please try disabling Autoptimize temporarily and see if the gallery appears?
If so you can review the Autoptimize documentation and settings to adjust the javascript minimisation so that it doesn’t break FooGallery.
If you’ve ever used the WP-Rocket caching plugin it has some great documentation on why minimisation can break javascript and how to make adjustments to fix that.
Let me know how you get on.