I made SMBC yesterday and stored it in the fridge overnight so I could ice the cake today. It had to be delivered today. I took it out, let it come to room temp, mixed it and it fell apart. It became loose, grainy and slippery. What happened?

all i use is SMBC but that has never happend to me, but i have heard that if that does happen to run it in the KA on high speed with the wisk, then slow it back down with the paddle, hth!!

baby