Zen-Grids background grid non-functional in responsive layout

Applies to: Drupal 7x.5.1, Zen-Grids 1.4

Further to this post: https://drupal.org/node/2127205 -- The background grid displays only a single column in responsive layout.

1) Import the background grid into _responsive.scss just before the @if $zen-reverse-all-floats == false statement: @import "zen/background";
2) Include the zen grid background in the main container where you want the grid displayed:

#main {
@include zen-grid-background;
}

The resulting image is a single column image that spans the entire width of the div. These same steps in _fixed.scss yield the expected grid. I could not find any documentation for this behavior or confirmation of the issue. Please clarify as the background grid would be helpful in responsive as well as fixed layout.

Thank you...Van