When I am typing the letters “fl” together come out blank… e.g. flea, fly, flip, flan - no fl shows.
Because you have enabled the ligatures (liga) OpenType Feature, but have not defined any glyphs for fi, fl, ff, ffi, ffl, ligatures. This feature is enabled by default in Word, etc., so if you don’t wish to add it, delete the blank fi and fl characters from your font.
Open the Preview Toolbar (F8) and disable the feature, or add the glyphs to your font.