As the screen width shrinks the images (correctly) reflow to fit the available space.

The first problem is how the order of those images is determined. The user expects that all of the images in the top row would logically appear first, in sequence, then the second row of images would appear, again in sequence.

What actually happens (and is logically correct if you inderstand how the tool is interpreting the content) is that everything in the first column appears first, then everything in the second column. This results in 4 images in the first column, followed by 2 images in the second column, no longer in left-to-right sequence, rather than 2 columns each containing 3 images

This issue can be corrected simply by using multiple rows of content rather than just columns. The second issue then presents itself, and this does appear to be a bug.

When the 3 column x 2 row layout is used to display these six images, if it displays 1 image wide x 6 images long they appear in the same left-to-right sequence as the original, but when the width is in-between it displays 2 columns of images - but rather than displaying the logical 3 images in each row it again displays 4 images in the first row, followed by 2 images in the second row with a GAP between them.