Case 1081704, beta3. When I add a script to a gameobject the inspector says "Missing" for the script and the console gets the following warning: GameObject (named 'GameObject') references runtime script in scene file. Fixing! UnityEngine.GUIUtilityrocessEvent(Int32, IntPtr) Additionally when I press play the console gets errors like: TypeLoadException: Could not resolve type with token 01000036 (from typeref, class/assembly Utils, System, Version=0.0.0.0, Culture=neutral, PublicKeyToken=null) And additionally the console is occasionally spammed with mysterious TypeLoad reflection errors from random/various classes/fields like: CameraController/<SmoothAttachRoutine>d__38 : Invalid type CameraController for instance field CameraController+<SmoothAttachRoutine>d__38:<>4__this The minimal project plays fine and can even make builds fine though. This all gets fixed if I delete all the asmdef files in my project. Are asmdef files unusable in 2018.3b3 or what?