Right now I am working on a project where I have a road network, and I have a layer with points on a bus route. I am trying to trace these points along the road network to create bus routes. It was working fine for the first few routes I did, but then when I started another route, it started acting really weird. It won't really go along the road network anymore, instead creating erratic lines that don't go along anything, often lines that don't even start where I originally click. The coordinate systems of all my layers are the same. What's happening here?