As far as I can tel, style change detection is not working in v.2.3.0.
We are sorry to hear that you have this issue. Thanks for providing the files for comparison. We’ve checked them and can confirm, that style detection is not working in the GroupDocs.Comparison for .NET version 126.96.36.199, regardless of whether or not a “.EnableStyleChangesDetection()” method is specified in the widget.
Because style change detection is working well for the same files in the GroupDocs.Comparison for .NET version 188.8.131.52, we consider this issue as a regression bug. Our developers will start to work on it.
We will notify you in this forum thread when the problem will be solved.
Sorry for the inconvenience.