I posted it on AnswerHub as bug report, in case someone here had the same issue: "Torn" static mesh on Gear VR with GLES 2 - UE4 AnswerHub
I have a mesh of 45k tris (or something around that number). One surface, one material, one texture.
In the Editor it shows fine with GLES2 preview mode:
However, on the device the mesh has holes/artifacts:
Why is this happening ?