SourceMaps with Create React App

I have gone through the following medium article and was able to upload all my sourcemaps to sentry.

However, when i triggered an error in my app, sentry was still unable to show the unminified line of code where the error occurred. Screenshot below:

Shared with CloudApp

My question is why is this happening and from where can I make sure my sourcemaps are uploaded successfully and to the appropriate place.

Thanks in advance