Okay, I have had disaster with fondant and cream cheese in the past. Twice I have tried to cover a cake in cream cheese then apply fondant polka dots to it. It works for a little while then the dots slide right off.
So I have vowed never again.
BUT.... I have a client ordering a cake with 100 cupcakes. On each cupcake she wants a monogram L wrote on a round piece of fondant (like pink cake box does). The problem is she wants red velvet with cream cheese icing. I did a test run by cutting out a circle, letting it dry until it was super hard, then placing it on top of the cc icing. Guess what? IT SLID! It just creates a slime.
Is it my recipe or what?!?
It definitely sounds like your recipe. What is your recipe? Although I must say, it's confusing if you say your recipe indeed crusts. What are you using to stick the fondant onto the cc icing, are you just placing it on top or using water/bc/etc. to adhere it??