vermeerpaul on "[Plugin: WooCommerce Custom Product Data Fields] Style sheets and Java not loaded"

Your repository is missing the 'min' assest files, where your code refers to them in class-wc-product-data-fields.php LINE 45/47. As a result your code doesn't render properly (and is missing critical image handling code)

SIMPLE WORK-AROUND:
WAS: (--)
45: wp_enqueue_style( 'wcpdf-main-css', plugins_url( 'assets/css/wcpdf-main.min.css' , __FILE__ ), array(), '1.0.2' );
47: wp_enqueue_script( 'wcpdf-main-js', plugins_url( 'assets/js/wcpdf-main.min.js' , __FILE__ ), array('jquery', 'wp-color-picker', 'jquery-ui-datepicker'), '', true );

REPLACE WITH: (++)
45: wp_enqueue_style( 'wcpdf-main-css', plugins_url( 'assets/css/wcpdf-main.css' , __FILE__ ), array(), '1.0.2' );
47: wp_enqueue_script( 'wcpdf-main-js', plugins_url( 'assets/js/wcpdf-main.js' , __FILE__ ), array('jquery', 'wp-color-picker', 'jquery-ui-datepicker'), '', true );

BETTER: Create the min files (using an online .JS formatter) and drop the missing files in the assets subfolders, being part of the ZIP distro.

https://wordpress.org/plugins/woocommerce-custom-product-data-fields/