Letters with diacritical marks missing when font used in web project

I've activated the Brandon Grotesque font and added it to my website via the link tag. I'm sure it's added properly and most of the letters look fine except for the ones with diacritical marks (the website is in Croatian). I thought this font had support for these letters because when I test out a word in the "Sample Text" input field, it renders fine but on my website it does not. What's going on here?