I have already discovered sectors 10 to 16 it archipelago, bought 10 to 14, cleaned 15 from bandits and now I'm in the middle of cleaning 16, so I should be able to discover the new desert sectors.
But every time when I send explorer the message about new sector discovery appears but nothing hapenns, and there is more actually after I send first explorer in day (I'm not sur yet, what resets it if it is midnight or just long offline time) sector 16 become hidden again and is uncovered imidiately when the explorer returns and then the "new sector -> nothing happens" loop continues