AppBar Has No Color Back From Detail View

[rabyunghwa]

Hey. There seems to be a bug which is very annoying. When you scroll up, the app bar disappears. Then you tap on an item to go to the Detail View. And when you hit the back button to navigate back(at this moment, the app bar is still hidden

), and then you scroll down, the app bar would appear. The problem is: the app bar has no background color. When you scroll a little bit more, the background color would appear. Is there a way to fix this issue? Thanks.