Hello!
It appears that instanced static mesh components attached to a Blueprint will never render in editor, or in game, regardless of whatever visibility flags have been set.
Thanks!
Edit: I’ve followed up some older threads on here that suggest adding the component at run time - I’m doing so using Add InstanceStaticMeshComponent, but the component is still not rendering 
i understand this was posted a long time ago but i found this while searching for an answer to the same problem and managed to solve it on my own. when you are inside the actor blueprint and you select “instanced static mesh” from the add component menu. from there you select the mesh from the static mesh dropdown in the details tab. from here is where the misunderstanding is found because you expect the mesh to pop into the viewport when you select the mesh however this is not the case. you need to drop down to the Instance section of the details tab and hit the [+] button to add an instance to the instanced static mesh component. without it you are referencing the selected mesh 0 times which is why it doesnt display in the viewport or in runtime environment.
You saved my day.
I guess it is little late but you should add one index to array to make it showup
