Bug When Unity try to play timeline, the Android App is shut down

I'm struggling with fixing the crashing issue in unity android.
For unknown reasons, sometimes app is crashed with error 'null pointer dereference'
In editor, it looks fine. But I tested it in both android phone and bluestack, it occurs.
It occurs with not only specific timeline, sometimes it occurs with A or sometimes with B.

Here is the error log I got.

And Here is the backtrace of it.

 

Hi.. i have the same issue. Did you found a solution?