To reproduce:
1. Import the package attached, open the project, go into the testScene. press play.
2. In game scene, press F, you will find the UI prefab is loaded. press F again, you will find the position of panel is reset.
3. If you disable the two setActive statements in start and update in script, or just delete them, you will find it turns to be OK. Press F once, and the position is reset at once.
4. Besides, if you use recttransform.anchoredPosition to replace recttransform.position, then everything is oK in both the two situations mentioned above.