I think I found a bug. Here is what I did:
I found Li WITHOUT having first found the broken submarine.
After alot of play, I lost Li.
Before going on, I decided to gather supplies. In doing so, I happened to swim past the sub.
When I did, the corner map flashed blue and on the main map a blue circle appeared where Li is first found. I went there in case something new had popped up, but nothing was there.
I think the game has some logic like "if Li is not in play and Naija is at the sub, mark Li" when it should be "if Li has never been in play and Naija is at the sub, mark Li".