External player doesn’t work

Hello.
I have Kodi 17.1 on tablet Samsung Galaxy Tab A 10.1 (2016) (SM-T580) with Android 6.
I’ve configured external player MXPlayerFree with playercorefactory.xml.
I try to play videos with smb from NAS, but I see only some controls (play, hold and so on) blinking in upper part of screen and that’s it.
Can someone suggest what do I need to do?