Hmm, this is quite a strange issue. Do you use Mass Markings that are not original to the game? The only thing I could think of is to try redownloading the marking pack and replacing all the current texture images and CFG file. Also, make sure that all your marking images are in the textures folder within the media folder in your FeralHeart folder. Also make sure that the markings.cfg file is in your FeralHeart folder.