Yeah, first make sure there are no errors with the geometry. Also, I've noticed that swift loop is a little buggy at certain camera distances. Sometimes I need to zoom out on the object to make it recognize the loop.
I am trying to use swiftloop on my model but it is for some reason only allowing my to do the command on certain parts of the model. Or in other words I cant get it to loop around certain faces of my model... any help with this matter would be greatly appreciated.
Make sure you have all the verts welded, there aren't double faces (lamina faces), there isn't an extra vertice in the middle of an edge, the normals aren't flipped on that face, etc. Every time I've had loop select not work it was because of some type of topology error that broke the polygon strip.