NOTE: After additional investigation this bug has been updated from the original description

The Start and Select button on Pro Controller are usually assigned to the - and + button. But on UWP, they are assigned to the sets below it (See image)

UPDATE:
The - and + buttons do generate the proper "Select" and "Start" input, however, the "Capture and HOME" also generate the same input, even though they aren't part of the Pro Controller layout. Also, pressing one of the face buttons, e.g. B, triggers to button presses.

The Input Debugger shows the correct input is coming from the Platform, and so these seem to be issues either in the test scene or Input System itself.

Repro:
1. Download package and project from: https://github.com/Unity-Technologies/InputSystem
2. Build UWP player for Input Test ( Assets -> QA -> Input_Test -> Scenes)
3. Connect a Pro Controller and launch the UWP app
4. Switch to Gamepad Diagram from the drop-down menu, or press Ctrl + 4
5. Press the - and + button, then press the buttons below them.
6. Press the face buttons: B, A, X or Y

Actual: The input displayed in the app doesn't match the actual input nor does it match the values reported by Input Debugger

Note: For Pro Controller itself, this is not a big issue, for Start and Select are still accessible. However, when using other controller emulating a Pro Controller, like 8BitDo, the set of Select and Start buttons are complete useless, and there is not way to generate the input.