WPF – Image ‘is not part of the project or its Build Action is not set to Resource’
Try doing a full rebuild, or delete the build files and then build the file. Visual Studio doesn’t always pick up changes to resources, and it can be a pain to get it recompile. Also try using a full URI as that helped me when I had the same problem. Something like pack://application:,,,/MyAssembly;component/bug.png