In 2017.3b5, it is now impossible to create or modify any prefab that contains RectTransforms, because the editor corrupts many of the RectTransform values every time the prefab is saved. A similar thing happens when you save a scene with a prefab with RectTransforms in it. Here is the bug in action: My questions here are: 1) Is everybody else seeing this, too? If not, then maybe there's something I can change about my local setup to get around this. 2) Does anybody know of any temporary workaround? I simply must modify and create prefabs to finish our workflows. Thanks!