Issues like this may be caused by either a conflict with your theme or with another plugin. You can read more about plugin and theme conflicts in the documentation here: https://docs.woocommerce.com/document/woocommerce-self-service-guide/
The best way to determine if the issue is being caused by a theme and/or plugin is to do the following:
- Temporarily switch your theme back to the Storefront Theme.
- Disable all plugins except for WooCommerce – you can try to leave Rede enabled, though I don’t have experience with it. Temporarily enabling PayPal or Stripe which are built in seem to be better options for testing at first to see if the box loads.
- Test to see if the issue has been resolved.
If that resolves the issue, then slowly re-enable features until you find the one that’s causing the conflict.