My sister went to a wedding and the only think I can think of was the fondant on the cake was too thick. The bride and groom couldn't cut the cake they ended up stabbing the side to get out a small piece for the ceremonial piece. And the staff peeled off the fondant prior to serving so there was absolutely no icing whatsoever on the cake. Could too thick of fondant be that difficult to cut?
That's hard to say. They could have mixed in some GumTex or Tylose so it was more gumpaste.
I would think the thicker it was the less it would dry/get hard.