I suppose the temperature of the ginger juice & milk mixture was not in the correct range for the gel to form. To make the dish reliably, I suppose one would n

I suppose the temperature of the ginger juice & milk mixture was not in the correct range for the gel to form. To make the dish reliably, I suppose one would need to make several servings, use the same volume of ginger and milk for each, and adjust the temperature of the milk to achieve the correct temperature of ginger & milk mixture. Unless you're lucky, the first one or two servings won't set. If their temperature is too low, you could try to use a microwave oven to heat them to the proper temperature.