When top stitching with a magnetic snap, put your walking foot (even feed foot) onto your sewing machine. It helps feed the fabric through and helps prevent the magnet from sticking to your plate.
Top stitching with a magnetic snap in the fabric always makes me a bit nervous. It can stick to your plate and stop the fabric from flowing evenly. I came across this by accident. I had the walking foot on for another project. I don’t know why I hadn’t thought of this before! I usually have another piece of fabric or masking tape over the magnet to stop it sticking, but combined with the walking foot, it fed a lot easier and stitches were a lot more even. I hope this tip has helped you too.