After I finished the first set of missions in story mode, I could not do chapter 2 because every special was locked. This happened after I unlocked a few specials, hit a few eggs with a hammer, closed the game and came back later.
Same issue here. Played the first 3 chapters on my first run, hit a bunch of eggs with the hammers, and the next day when I came back to play, all specials are locked, making me unable to play the game at all (as it requires you to choose a special to advance).
Similarly, when I go to Gatcha, there are no hammers, so I cannot even exit that page and need to restart the game.
This essentially makes the game unplayable after first playthrough, which is not just a "small" bug.