Image gallery block not displaying video thumbnails on mobile 7.1

Hello,

I'm having two issues, both video player related on the homepage of the site. 

1. The first issue involves a display error with a carousel gallery block while using mobile. I am using linked YouTube videos with custom thumbnails.
   
   The carousel gallery block displays the thumbnails while in desktop mode, but when viewing on mobile the thumbnails disappear—making it appear as if there is no content.
   
   While troubleshooting, I previously removed all of the custom javascript and CSS to see if that was the issue, but it didn't appear to have an effect.
   
   Any idea why the thumbnails disappear on mobile view and  how to correct this display error?
    
2. Secondly, the main reason I am using custom thumbnails is so that I can assign a custom video play button. 
   
   The play button appears while I'm actively editing the CSS, but it doesn't display when I close the CSS editor and preview in the browser. 
   
   I have used this technique for custom play buttons on several other 7.1 sites, and never had this display issue.
   
   Does anyone know why the custom buttons aren't displaying in context? When I inspect the code in the browser they are present, but not visible. 
    

Thanks in advance!

Squarespace 7.1 Site
https://orb-flower-ctgc.squarespace.com/
password: evanb

cc: @paul2009@tuanphan