I just made a big cake. After baking each layer, I froze them. Took them out a few days before, leveled, torted and filled them, crumb coated them, and frozen them again. Took them out the day before, SMBC on them, decorated them and outside on my unheated porch, just above freezing, all night. Transported cool, then when stacking using the SPS. System, which was already in the tiers, The icing on the bottom tier cracked in a number of places. They weren't big cracks, they were tiny hairlines, but I could see them.
Thankfully, in a cake of this style, they were easy to camouflage, but if this was a super smooth BC cake, it would have been a disaster! I got some good advice, like it can't go from freezer right to room temp, and maybe the stacking did it, but Maybe it was the transporting that did it? Any other ideas would be helpful! thanks,