Hon, I would not use your darning foot for SID. That foot is for FMQ and until you get used to FMQ you will get skips like that, and loose control over the stitching.
FMQ is where you drop your feed dogs and move your fabric all around underneath your needle. We do this when we want to make circles, feathers and other shapes.
SID is following your seamlines
Cross hatching is usually stitching diagonal lines across your quilt.
You can cross your stitching lines when you SID :D:D:D
It is NOT a hard and fast rule that you can't cross your stitching lines when you FMQ either :wink:
If you don't have a walking foot, use your basic sewing foot for doing SID :wink: I think you will be much happier with your stitching. You will have MUCH more control over where your stitching ends up :D:D:D
If you don't have a walking foot, it is a great investment :D:D:D