The media queries built from the breakpoints are not defining the min and max widths correctly.

We recently updated the breakpoints so that the point establishes the lower bound of the breakpoint, not the upper. The code the produces the CSS from the breakpoints and grids still assumes the breakpoint is the upper bound.

This code lives in layout_breakpoint_get_css of the layout.module file.

Here is an example. This page should have one column i.e. no sidebars.