Perhaps it is intentional, but when you add col-auto, or col-{breakpoint}-auto for that matter, it automatically removes the element's gutters.

In my case, the first column has col-auto. It indeed fits to its content, but since there are no gutters defined for col-auto, it fits the outer edge of the row parent. As a result, it kind throws off the general flow and style of the row/column formatting.

I feel it would be beneficial to keep gutters intact regardless of whether or not a column is given a specified column length or set to auto. For the time being I have manually added in padding.

I couldn't find any other issues for this matter, and documentation makes no mention of it either. In the examples, they use col-12 on top of col-md-auto, so the element conveniently gets the padding from the col-12 class.