When moving actors spawned from within the editor to a new sublevel, their meshes stop rendering. However, if you open a new level then re-open the old level the meshes become visible again. You will also notice that after the first clone is made, the original actor's mesh also disappears.
Versions tested (issue occurs on all versions):
4.18.3 - CL 3832480
4.19.2 - CL 4033788
4.20.2 - CL 4302132
Result: The meshes stop rendering.
Expected result: The meshes should continue to be rendered.
There's no existing public thread on this issue, so head over toAnswerHub just mention UE-63875 in the post.