So after a series of disasters I found my population much reduced. At the same time my reputation with the Empire had dropped and I received a message that immigration would be restricted to labourers, and then, suspended entirely. By then my settlement was large enough that I built a Foreign Office and restored my relationship. I received a message that partial immigration had been re-approved, then full immigration. I raised prestige with the Clockwork Empire to 100%. Even so immigration has not actually recommenced. Not a single worker nor overseer has arrived since the suspension in many days.