I downloaded Bricks (v.1.5.1 RC) and noticed that you can only click below the icon to switch between breakpoints, and not on the icon itself, it looks like the the HTML structure for the links are setup incorrectly, see video link: Custom Breakpoints link clicking not working in the right area
I’m happy to say that it was an extension I added to Bricks Builder, not Bricks Builder itself, I’ll give you more details on what extension made the issue appear.