Adding Cyrillic letters to an existing font

Hi, I’m a complete newbie here so please bare with me… I need to at Bulgarian letters to an existing font. I’ve created it and it all looks great within Glyphs 3. However, my updates won’t export. They have been selected to export but still nothing is happening. Can someone point me in the right direction please? TIA.

This may be a font cache problem. Read this please: