It used to be these missions generated for any faction, not just the owning faction. That changed in update 5. Before, every single system had restore missions because there are always inactive settlements. Now, they only generate missions where the owning faction is located within the usual BGS rules. Which is less frequent.I think this is due to how the BGS works. Restore missions are highly sought after be players, and enough players do them, the settlement will switch to online the next tick and will stay that way unless it gets repeatedly shut down again or shuts down due to a general BGS state change. So in short: If you want restoration missions, shut down a bunch of settlements repeatedly to generate some.