SteamVR Input and Vive Trackpad axis tracking issue

I have to be doing something wrong. I’m trying to setup axis mapping for the trackpad on a VIVE but no matter what I can’t seem to get valid input to register. My binds look like this:

According to all the documentation I can find, I have to have the two binds for the _X and _Y and that should create the special vector bind for SteamVR. I then Regenerate both Action and Controller bindings then reload the manifest. Finally I launch SteamVR’s setup.

The controller is set to be used as a trackpad and I go to setup the position bind and:

I would expect MotionControllerThumbstick_Left and MotionControllerThumbstick_Right to be here but nothing. What do I have to do to get it to put these in there?