Using Unity 2018 3.0 The bug happens on both iOS and Android. We have a nested UI (several menus that activate each other etc.) On editor it works on all resolutions. On devices the UI shows in a different location. We tried changing build modes, switching between Overlay and Camera UI but the bug still occurs. Our current solution is to deactivate the root UI game object and have another GameObject that has a Coroutine to WaitForEndOfFrame and then activate the root UI GameObject. It works now but I am sure that this is not the correct solutions as it seems a by-pass for other stuff in the Unity Game Engine to load.