Welcome @allseeinglemon !
So I took a look at your page, and I think I see the issue. It looks like one of your boxes has opacity: 0 on desktop and then opacity: 0.39112 on mobile.
I changed the name of your element within the Layers tab to make it easier to find, feel free to change it back.
The way I found this is by using the JSON view to see all content associated with each block. If you right click on a block in the left Layers tab and select JSON view, or select an element and click command+e, you will see all Builder-related data on that element as a JSON.
You can manipulate the JSON directly (though watch for syntax!) or just use it to find any issue and make the change in the Style tab, for example.
I am not sure where that styling came from, most likely from wherever you imported from, but it should be an easy fix! Try it out and let us know if you have any other questions!