Landscape texture bug ue4

Hello everybody, first I want to say that I don’t very good speak English.
I packaged today a game for android and all the game work but not just one thing: the landscape texture has a bug and the texture ist black and grey. I tryed to rebuild all my game (that take a looooong time) but no result and I seted up all the android sdk, ndk, jdk correctly .
Pleas help me!