Select Field on Form Doesn't Show Selected Options

It is a color/styling issue. I suspect SS does not have enough fine grain control for the colors you have selected.

Add the following to Page Settings > Advanced > Page Header Code Injection for the page. Please see per-page code injection.

<style>

  #select-2f66ff43-e150-4e0a-86e0-c400d80e426c-field {
  
    background-color : transparent;
    border-color : white;
    
    }
    
  </style>

Let us know how it goes.