I just made my first font for a project. They are symbols for dice, regular and extended. I can type the letter A, get the 6 Die in 10 pt., the letter s and get the 5 Die and so on, G gives me a 10 sided die, and H gives me a 20 sided die. When I change it to 12 point, the die disappear and reverts to cryllic test and the die is no longer there. What am I doing wrong? 
When you started with an existing font, you might have to remove some unsupported tables like VDMX, LTSH and hdmx. If that doesn’t help, remove the hinting. Do let us know your result.
I started over and made the symbols smaller and they worked fine.