Warning: Shipping method required! - Delivery method checkout cache bug - OC 3.0.3.2

Hi,

On the checkout page of www.4rissa.com, there is an error during checkout at the "Delivery Method" step, the error message is:
Warning: Shipping method required!

Site is using OC 3.0.3.2

I believe this is a cache bug, clicking "Continue" button with shipping option selected does not work and checkout cannot be completed. Checkout only works after I clear the browser cache every time of going through checkout.

I would greatly appreciate help with step-by-step instructions to fix this, thank you so much everyone!

Rissa

Could be this issue.
https://github.com/opencart/opencart/issues/7008

Fix for above issue.
viewtopic.php?f=201&t=207498#p737358