Levi discovered this phenomenon when he first entered the Ashen World. Only the storage space that contained dead things could be opened. (See Chapter 215 for details.)
Unless the transcendent creature space was built on other planes, it could not be opened on other planes.
So far, according to the wizards' research, there were only two types of living spaces that could be opened without the restrictions of any plane.
The first type was a Spiritual Space similar to the School of Spiritualism. This kind of space was rather special. It was opened up in the body on its own. It was equivalent to space being a part of the body.
The second type was the "Legendary Demiplane" of Legendary Wizards. Needless to say, it was essentially a higher-level internal space.
Watching the transcendent creatures gradually disappear into the forest, Levi turned around and left.
...
Holy Brilliance Calendar Year 1130, Month of Flowers.