A wolf and a penguin could never live together, nor could a camel and a hippopotamus. That would be absurd.
And the older you get, the fewer things you really love. And by the time you get to my age, maybe it's only one or two things. With me, I think it's one.
Let's imagine the following: It's my turn, I choose the action "increase army". My byzantine army consists of one and only one cube on the regulars space. Now I want to move this cube to the elite space by paying three besants.
What does happen in the moment, I take this cube in my hand? Does my byzantine army disappear immediately from the board, because it has no more cubes anymore for a logical second? I does it stay in the board?
My understanding is that the army would only be removed if it had no cubes in it at the end of your turn. So it would stay on the board in your scenario.