Another issue that came up in https://developer.blender.org/T65560, is the fact that it’s currently quite hard to add unlinked Collections into the scene.
If you created Collections by adding them to objects in Properties > Object > Collections, they won’t be added to the scene.
If you could right-click in the Outliner and pick ‘Link Collections’, which would spawn a list of unlinked Collections, that would at least make it much easier to do so.