The docs mention BaseParts could be a Terrain or SpawnLocation. Do these also have AssemblyRootParts?
Also I believe if a BasePart were part of a Model then its AssemblyRootPart would not necessarily be itself, but the AssemblyRootPart, typically PrimaryPart, of the model. But if that were to be destroyed, Id think it would revert back to this BasePart. So idk