i have 3 objects that disappear when i play the level and depending of the distance of the camera, the normals are fine , are put in visible , i dont understand what is the problem.
Check if you probably have some culling volumes in your level or probably you are using lod’s 
- which type of mesh do you use? e.g with the foliage tool, very small mesh,…?
i dont use LOD , are static meshes , where can i see the culling options? thanks and sorry for me english.
-check in the scene outliner if you can find a “cull distance volume”
-make sure that you are using the “epic” quality settings
-could you probably share one of those assets so that we can take a look at them
ok thanks , work, but i dont remember activate nothing xd
Coming here after 7 years since last comment on this thread,
I just want to give another case where skeletal mesh object seem to disappear, we might want to check our physic asset assignment on our skeletal mesh whenever we decide to rename the skeletal mesh asset and physic asset.
posting this just in case I forget about this issue and going back googling for answer. 