When embedding a font you have to add four font files to get the entire font. One file each for Normal, Italic, Bold, Bold-Italic. Not all fonts come with all files (glyphs). Arial Rounded MT Bold for example is Bold only, so you either have to borrow the other three files from another font (or fonts) or settle for Bold text throughout the book. So perhaps Blossoms font doesn't have all the files (glyphs).