So i have just played a normal game where we didn't get a dragon soul after killing 4 drakes. I played with a friend who noticed it, because i had no idea how the new dragon system works. An enemy noticed too. Is this a known bug or did i miss something?
If Shaco's (or any) clone is the one to deal the killing blow to a drake, it doesn't count towards a soul. This is a bug and is reportedly being fixed next patch.
This is correct. We have a fix in for 9.24.