No animation when reenter app

[DanteAndroid]

trafficstars

I met a weird problem when using placeholder and collapse toolbar animation. The code is just like yours, and the effect is great.

Problem only happen when I press back to quit app: The collapse animation just gone(toolbar just turns to normal height suddenly). When I swipe from recent tasks then enter app, it works well. Any idea will be appreciated!

[DanteAndroid]

I found the tabs layout's animation is gone too in that situation. So this problem has nothing to do with cold start. Could you help me.