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 - Asset Creation - Unreal Engine Forums
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:
http://s17.postimg.org/5pcvip166/gles2_for_gearvr_editor1.jpg
http://s17.postimg.org/ok8m9417y/gles2_for_gearvr_editor2.jpg
However, on the device the mesh has holes/artifacts:
http://s8.postimg.org/blkx1iwhg/Screenshot_2016_03_15_21_08_17.jpg
http://s8.postimg.org/iijorsi5w/Screenshot_2016_03_15_21_08_28.jpg
http://s8.postimg.org/tscemqn78/Screenshot_2016_03_15_21_08_45.jpg
http://s8.postimg.org/osad11s6s/Screenshot_2016_03_15_21_08_52.jpg
Why is this happening ?