If you use a custom font with a UI Text and set the color to white, when you build the player, the text will become black. If you do File > Save, the text will revert to white. Note, this only occurs in the editor, the built player is fine. This appears to be a 2018.3 regression as it occurs in 2018.3.0b8 but does not occur in 2018.2.13f1. Note, I encountered this bug when moving FPSSample project's ConsoleGUI prefab to a different project. FPSSample makes use of the RobotoMono-Medium font you can get from google.