Hi,
no you're not missing anything. I thought that this feature no one use, so I don't get too much time to it, to create it perfect. So, you told that switching works fine, OK, so I added at least this:
when you select "Guide on" .. guiding will be enabled on nearest point on track from you.
From you mean: When you have enabled GPS, it's you location, if not, it's center cross.
Try and let me know if need any improvements.