I see the problem. I'm just wondering why this didn't happen before?
That's why I can't be 100% sure. The bug is you have too many same abilities and they multiply each chapter you complete. So actually you have that dig ability, but the "book" is so full and others are in teh way. I still wonder, why this didn't happen before?
It should have happened for all the heroes in chapter 4, 5 and 6.
Ay, ay, yay.