Experienced a similar thing. In my case it was because a sub folder in the Eclipse workspace was overwridding the build settings - which was something it decided to do itself. Have a look at the command line used for the file that is not building, and you will probably find it doesn’t have the options you list in your post. Do any of the folder icons in the Eclipse browser look different to any other? If so, right click on it, then in the pop up menu select the configurations option and click ‘reset to default’. Then it will just inehrit the compiler options from the project.