There’s a known “bug” with official Unity cubes as scaled/rotated children. If you import your own cube model, it should be fine. Or just get some free crates from the Unity store and change the textures.
The “bug”, last I looked, is that rotated cubes have the rotation baked into the model, to run faster. When it has to go through a complex chain of parent rotating/scaling, that trick throws the order out of whack. [To check this, print the raw verts of a rotated cube – unlike any other model, they are changed.]