I tried to make the turkey cupcakes pictured in the Betty Crocker ads (the ones with the candy corn tails and beaks). When my birds sat overnight the candycorn melted. The only thing I did that I can think might have caused this is I used homemade chocolate buttercream icing instead of canned frosting. Has anyone made these using canned frosting? Did they candy corn still melt?
I haven't made them, but when sugar touches liquid, it will melt. It could be that your homemade frosting had a higher liquid content than the canned icing. Or it could be that Betty Crocker just didn't warn you that after sitting overnight, the candies will melt.
The Halloween cake that I made had home made BC on it, and i used candy corns for the border. Even after the leftover pieces sat for a few days, my candy corns were still ok. Not sure if the chocolate made a difference. Sorry this happened to you!