Glyphs Mini not exporting new glyphs

I am trying to update a icon web font, following this tutorial:

However, I am adding to an existing font, and when I export the font my new glyphs are not showing as available.

I can find them if I open the font in Glyphs of Illustrator, but not anywhere else. And, despite using unicode names (e.g. “uniE74G”), unicode reference is not working from the css.

Furthermore, if I open the exported font in the full version of Glyphs (trial), the glyphs appear in the list, but are empty if I try and edit them!

Any help would be appreciated. Thanks!

UPDATE: I think I figured it out! I think I may not have used proper unicode assignments the first time.