Minor - UEFN - player can build before live edit starts, inside FN

Right before you get access to live edit, you are given the phone. If you place anything during that time, it will save on your level, just far away from it (if a large prop, it will affect memory). This should normally not be allowed, to avoid adding unnecessary props into your map without knowing they do save.

Example below is what I added with phone before live edit was ready (building) and the map being in the background.
UnrealEditorFortnite-Win64-Shipping_QwWQkY62Ao

I have a feeling this also might be how maps get corrupted. You get the phone before the level loads and if you fail to get into the level, all your prop/asset bindings become invalidated, but in UEFN it all looks okay.

It’s just when you upload to Fortnite, your level is entirely gone.