If I remember correctly, Flash Text Engine (which TextBlockTextRenderer uses) has issues measuring certain fonts. Unfortunately, when that happens, I haven't found a way to fix it, other than using a different font. You could try playing around with the font size, to see if that makes a difference.
You might also want to see if it helps to change the width or height. If you've accidentally set either one manually to a small size, it will cut off the text.