Hello,
Try to add the next code in Theme Options > Custom CSS > Custom CSS for mobile:
.products-loop .product {
width: 33.33% !important;
}
.products-loop .product:nth-child(2n+1) {
clear: none !important;
}
.products-loop .product:nth-child(3n+1) {
clear: both !important;
}
Regards