I think you are drawing a distinction without a difference.
If something is void it is as if it never happened, but that is not to say it did not actually happen.
Suppose two thieves agree to split the proceeds of their crimes 50/50. One steals more than the other and wants to keep it. The other cannot sue to enforce the agreement because an unlawful agreement is void. But the agreement exists however: both entered into it. So it cannot be said that the agreement does not exist, it clearly does. But it is unenforceable.
As I said, a fine distinction perhaps.