@font-your-face no preview

Have got one ttf font working however I had some problems getting a preview which I thought was fixed by removing spaces in the name, however after trying to add a second local font, it's showing just the regular san-serif in the preview regardless. Thought the preview might be bugged so styled it anyway but it's san-serif. If it doesn't work in the preview, it doesn't work in css either. Can't see any known issues atm, I've added the module via backdrop instead of installing manually.