Hi there Philip,

It must have something to do with recent changes in <column> component and the fact they temporarily do not fall back to the .col class in case of lack of props. While it is being fixed, it is fairly easy to deal with the issue instanlty, at your end. Adding it manually should solve the issue for a single column, but to have it all the way it was please edit className() at src/components/Col.vue, line 47. Make it start with 'col', like so:

data() {
    return {
      className: classNames(
        'col',
        this.col ? 'col-' + this.col : '',
        this.sm ? 'col-sm-' + this.sm : '',
        this.md ? 'col-md-' + this.md : '',
        ...

Depending on the use case, you might need to rebuild the app (yarn build). Thanks for taking time and letting us know!

With Best Regards,
Kuba