Adding Static Image to WooCommerce Content-Single-Product template

Many thanks to Nathan Powell for the fix.

Changing get_stylesheet_directory() to get_stylesheet_directory_uri() will return the correct URL.

get_stylesheet_directory() returns the absolute server path to child or parent theme (hence my previous issue) whereas get_stylesheet_directory_uri() returns the properly formed URI of child or parent theme.

I suppose the lesson is to pay close attention to exactly what function you’re using as WordPress has many similarly named plugins.

You can check out the codex docs here:
get_stylesheet_directory() & get_stylesheet_directory_uri()