| I am quite sure this is a bug, it has to do with the game placing two crystals in one slot, even though you don't see it so when you get to the fourth you actually don't have any left hence the problem.
I think it was solved with the patch, so download it, install, restart your game and it should be fine because it will edit your saved game automatically, fixing the problem. If not, then the only solution is to go to the previously saved/backed up game, that is if you have any - I tend to back up my saves even though I do have the patch - it didn't solve all the issues out there. | 
Linear Mode
