I think that OnFontTextureRebuilt() is being invoked before the new font is actually added to the list of fonts being used by the mesh. Please help me test this by doing the following...
Go to the method "RebuildTextInfo()" in SuperTextMesh.cs and move this code...
if(!allFonts.Contains(Rebuild_font))
{
allFonts.Add(Rebuild_font);
}
to be directly below this line, earlier in the same for loop:
Rebuild_font = Rebuild_info.fontData != null ? Rebuild_info.fontData.font : font;
I think this should fix it, now STM will be aware of the new font before the first character in it is actually called, so it should be able to rebuild at the right time. If this works, I'll be sure the next update includes this!