Couple of things that you can compare between app and cloned app.
App Service -> settings -> Configuration -> Default Documents . Ensure the default doc is listed here and is above hostingStart.html
Compare Files of app and cloned app through kudu console
When Sitecore is deployed to Azure PaaS, XM and XP packages for app services contain additional config files for Application Insights in the folder \App_Config\Sitecore\Azure. The file \App_Config\Sitecore\Azure\Sitecore.Cloud.ApplicationInsights.config replaces default log file appenders with Application Insights appenders for standard Sitecore log files.