Hello Preamble,

Thanks for reaching out to us.

Please, add a screenshot of your sections where you want to apply this.

Thanks

HI, indeed, by default it switch to single imge per row in Mobile view. But using Custom CSS you can force to keep two columns in Gallery addon.

Example CSS

@media only screen and (max-width: 580px) {
  .sppb-addon-gallery .sppb-gallery li 
    {width: 50% !important;border: 5px solid transparent; margin:0 !important;}
}

it makes two columns, add small border between images, and in case of.. remove margin that user could set.

"6 + 6 columns in section" works OK but for single addons added in each column. This is BOX Grid, read more how it work in Bootstrap to understand the basics.

To avoid any streching of the image, what domension of the photos should it be? Should they be 4:3, 6:9 or square 1:1 ?

For Thumbnails set only one value for resolution, not both. Only height for example.