Is your 3CX license current? i.e. Have you renewed the annual Upgrade Insurance [UI] on it since it was first purchased???
If it's more than a year since you activated the license, and it has not had the UI renewed, then that may explain why you can't restore the system - especially if you are trying to do it onto a platform that is in any other status than exactly what your original was like ...
Let me know your status there ...