Exploration bug.
As the last event in Region 1, I found an Unknown Ship and was asked what I wanted to do with it. I chose the option to communicate, which would reveal two tiles in Region 1. I completely forgot that this was going to be the last event in Region 1, and the game then switched to Region 2 with no revealed tiles.
It was basically a wasted exploration event.
Ideally, what the game should do is reveal however many promised tiles in the next region instead. However, if this is intended behavior, then the Communicate option should be blocked, leaving only Fight and Trade.