I think I found a bug that stops you from progressing to the next expedition. In the first expedition, in the level with Boa, I went through the door without fully completing Boa's encounter since I ran out of energy, and after finishing the rest of the level, getting the 1st familiar, and seeing the 2nd expedition unlock, I instead replayed the first expedition wanting to fully scout Boa's encounter and hoping to see a new event. No new event, but then after completing the expedition again, the 3rd expedition unlocked, but at this point, the menu was playing multiple songs, and while I could select any of the three expeditions, I couldn't start any of them. I had to restart the game.
I really like the game though! I ended up spending much longer than I thought figuring out how to manage my energy and what to scout for. I'll definitely be replaying this to get to the expeditions I missed.