Dave - if I am understanding what you are saying correctly, are you pinching and expanding when the geofence circle is red? If so this just zooms in and out with map. If you then poke the pin in bottom right corner of screen, the geofence circle changes to green and it can then be expanded or shrunk as needed. I made mine as close to just covering my house as I could, so when I leave and return it locks and unlocks my front door. That parts been working great. Just don’t get the lock status update on my lock app (doesnt change the lock or unlock status on the tile as it should) but this is a bug they are aware of and working on.
P.s. you may have to pick up the location pin and set it down in a few different places to get it in the spot you want it before expanding your circle, since you can only expand in an even circle, as far as I can tell.