This is a font-related error. You’re probably using the default font in the PC build, which will not work in the OSX version. The problem is that when you create a new font, it builds a texture sheet for that font, and a material that you can apply to the GUI elements. When you don’t create a font other than the default one, it just uses your windows font system to pull in a default font- but a texture sheet and material are never created. When the project goes over to Mac, it’s going to look for the windows version of Arial. If you replace it with a different font (or simply make a font material/texture for the default one), it will work.