I am in the process of covering a cake with the MMF I made last night. I made 3 batches and two have turned out fine. One batch is not too stiff, doesn't seem dry but I can not get it to knead till smooth or roll out and get it smooth. It has little "crater" like places I can't smooth. I took a small piece and tried Crisco - no help; then powdered sugar-no help. Any ideas? Thanks in advance!

Try heating it up a little in the microwave.

Did that! It isn't at all hard to knead but I just can't get it smooth. I did try the Microwave first (forgot to mention in first post!) I wonder if I will just need to make a new batch. PAIN!