I see you’re setting Debug=true but since ASP.NET/IIS doesn’t have a console you can see the logs, you need to change the logger so you can see it in Visual Studio.
The docs cover how to do that here: Diagnostic Logger for .NET | Sentry Documentation
The SDK should log out what’s happening internally. Often when folks using IIS can’ capture events the issue is related to the server requiring a proxy to access the Internet.
This situation (and other common issues) are clarified on the troubleshooting page: Troubleshooting for ASP.NET | Sentry Documentation