In some really rare and inconsistent cases, there are problems with Windows 7/IE11 and Google fonts (Open Sans, Montserrat, …). In this cases, fonts won’t show up and instead, you will see just blank space. Unfortunately, we can’t fix that since it’s specific browser problem/bug. A workaround would be to use Easy Google Fonts plugin and add different Google font to the page and use it. Or you could just use a different font altogether.