mobile android devices start render is empty and no speed index

hi all,
I configured a Private Instance .when I use chrome ,it is works well and shows start render and speed index .
But I can’t get [start render] and [speed index] when I connect to android devices. I did check [capture video] in Test Settings tab and [Capture Full Size Video] in the chrome tab.And [enableVideo=1] in settings.ini.
In the result,I can’t see watch the video,it shows [Your video will be available shortly. Please wait…] ,but raw video is ok .
What should i do or check?