Holes in plane (ue4) but not in blender

Hello. I have imported a plane from blender to UE.
And get some holes in the mesh. I can’t find the reason why.
Normal recalculated,
Created Uv map, lightmap
In blender everything is fine,
but in UE - this strange thing is happening.
Can you help me find a solution?

if you have any modifiers you could try applying them prior to export.