Actually, the vertical thumbs on portfolio page in the 2 Column layout that you are using are given some extra spacing on the sides on purpose. You can see the same thing happening in the demo. Please scroll to the first portrait-oriented picture (portrait of a young man in neon lighting) and you will see it’s not aligned the same way as horizontal images. This is done on purpose and is a part of this layout. Otherwise, portrait-oriented pictures would appear too large compared to landscape-oriented ones. This extra spacing is intended to balance the visual ‘weight’ of vertical and horizontal images, and also provide some spacing and a light effect of controlled scatteredness.
So if you would like to achieve the same look and feel as in the demo, please start with a landscape-oriented picture rather than a portrait-oriented one.