HMD sound but no image after packing with 4.14

I`m building a large VR scene with the project is over 14 GB . First I run it in UE4 4.13 and it works quite well. Then I rebuild it in UE4 4.14 . And it works well in the editor . But after packing , when running the program , my oculus only has sound but no image ,and the HMD tracking also works well as the PC screen shows. That problem never happens in the UE4 4.13 ,that is to say , there is no problem after packing with UE4 4.13! Can sombody teach me how to solve it ?I need to use forward shading to optimize the large scenen. Thanks a lot !