What border are you talking about? There has never been an option to set the border width for individual frames to 0; if you don't want to see a border, simply don't set any statuses to show on the border. There has also never been any option at all to change the border width for the layout/backdrop frame.
I'm talking about the border around the entire grid, not each individual unit frame. I may have been able to set the opacity of the border to 0 before. I was able to hide it somehow.