Nested breakpoint-sass with Susy span mixin - css

Question

I use nested breakpoint with Susy. The compiled CSS contain the line: box-sizing: ;
When I don't use nested breakpoint the compiled CSS is correct.
The SASS code:
#include border-box-sizing;
#list {
$map: (
columns: 12,
gutters: 1/3,
math: fluid,
output: float,
last-flow: from,
global-box-sizing: border-box,
gutter-position: after
);
#include layout($map);
#include clearfix;
> li {
background: #BAC7D1;
margin-bottom: 2em;
#include span(3);
#include breakpoint(max-width 1099px) {
#include span(4);// this line make the problem: "box-sizing: ;"
}
&:nth-child(4n+4) {
#include breakpoint(1100px) {
#include span(3 last);
background: blue;
}
}
&:nth-child(3n+3) {
#include breakpoint(max-width 1099px) {
#include span(4 last);
background: greenyellow;
}
}
}
The compiled CSS (with the line: box-sizing: ;):
#gallery-list {
overflow: hidden;
*zoom: 1;
}
#gallery-list > li {
margin-bottom: 2em;
width: 23.40426%;
float: left;
margin-right: 2.12766%;
}
#media (max-width: 68.6875em) {
#gallery-list > li {
box-sizing: ;
width: 31.91489%;
float: left;
margin-right: 2.12766%;
}
}
#media (min-width: 68.75em) {
#gallery-list > li:nth-child(4n+4) {
box-sizing: ;
width: 23.40426%;
float: left;
margin-right: 0;
}
}
#media (max-width: 68.6875em) {
#gallery-list > li:nth-child(3n+3) {
box-sizing: ;
width: 31.91489%;
float: left;
margin-right: 0;
}
}
I've also used nested breakpoints with Susy in another site and it works well. I've also tried the susy-breakpoint mixin the problem remains the same.