I don’t know if this is your problem exactly but it does happen to me. I will be sewing and my machine stops. I worked out that it’s the connection from the foot into the sewing machine (Janome). I have to wiggle the connection or take it out and put it back in until my foot controller shows up on the screen and it’s all ok again. I took it to be repaired but was told just to put up with it as it doesn’t happen all that often. If it happened a lot l would look at getting it fixed somehow. Hope this helps.