Prefabs unpacked on instance - how to avoid

I am trying to use Addressables.InstantiateAsync using a (nested) prefab as an address. During runtime I understand the concept of prefabs no longer exists and that everything is unpacked. However, I am trying to accomplish the same thing in the Editor. I have a 3D tileset of prefabs and some PCG code to generate a level. It works fine, but the resulting tiling is "fat" and any changes to the prefabs will be lost requiring the PCG to be re-run (which may be expensive). Is there another way to "add" prefabs to my scene using addressables?
Some more context: This is a "regular" MonoBehavior script. I decorated it with a button in a separate script, so perhaps that is part of the problem.