I have the Crescendo and she sews just fine over the seams. I use the standard 1/4" foot. I also believe that your stitch length is too small and once the needle gets caught, it doesn't have the oomph to make it over the hump. You may also need a new needle.
There is the standard foot with the little spring at the side which is meant to be used with bulky items. Try that. You will have to move the needle to the 1/4" spot though.
As for the muveit foot: I ended up buying the open toe foot for it as the regular foot is too bulky for me.