Custom SCSS not being recognized [Gradle, Eclipse, Buildship]

I have a number of SCSS mixin customizations for various components that have worked fine for a long time.  I recently added a new simple mixin:

@mixin mc-section {
    .section, .verticalsection {
        background: #F5F5F5;
    }
}

The mixin above is included in the theme mixin with both @import and @include.  

I then ran "gradle vaadinThemeCompile" and refreshed my project in Eclipse and restarted Tomcat via Eclipse WTP.  The new addition was not present in the styles.css I downloaded via Chrome developer mode.  I use to be have no problems doing this back when our build was maven based.  Now that we are using Gradle + Eclipse + Eclipse Buildship it no longer works.  

Perhaps I'm sufferring from some kind of brain failure?

If I make changes to an existing scss file already known to work properly that change is not visible after I gradle vaadinThemeCompile.  So there is something I'm forgetting to do or the gradle vaadinThemeCompile is broken.

Config: Vaadin 7.6.8, Eclipse neon.1; Buildship 1.0.21, Gradle 3.2.1, Tomcat 8.0.33

I found the problem.  It was indeed brain failure.  I was not updating the right copy of the scss files. :(