I have remove the rule from parent and apply to ul only. The 1st 3 li items will be in columns and the others seems to display on the right of the screen. Compatible with Bootstrap 4
In bootstrap 4 col-md-4 will mean three columns across the screen so if you have more than 3 list items then they will wrap around to the next line and so on. That’s not a problem if thats what you want.
In the code you supplied you have missed out the row class on the ul which is vital in bootstrap. You cannot nest columns unless they are direct children of a row class which in turn is a direct child of the container class. This is a requirement of bootstrap.
If you use the correct structure then indeed your original code works out of the box.