It is not working after I reinstall BYOB. What is going on?

When you reinstall BYOB, Shopify will automatically change the App Proxy URL to /byob-[n]. You have to manually change it to /byob since Shopify doesn't provide an API to update it. In other words, we cannot automate this process at this moment.

1. From your Shopify admin, go to Apps => App and sales channel settings.
   

   

2. Click BYOB.
3. In the App proxy section, click Customize URL.

   

4. Change the proxy URL from /byob-[n] (n is the dummy number generated by Shopify) to /byob 
5. Click Save.

Reference:
https://help.shopify.com/en/manual/apps/working-with-apps#change-the-apps-proxy-url