I think perhaps melting them enough to pour into molds might be the problem. When making those cookies (many, many years ago) the chips of cookies were placed directly into the holes of the dough and melted in the oven.
They were in there only long enough to just, just be melted.
Only guessing here. Are the molds capable of being put in the oven or the micro? You could fill them with the crushed candy and let them become melted inside the molds??
What is wrong with fully melting candy before cooling it either in fridge or room temperature?So my silicone accessories are oven safe to a certain degree. The candy molds must be as well if you are pouring hot melted sugar into them.
Just an idea.