GameInput giving different responses across 3 different browsers

Win 7 service pack 1

Chrome 50.0.2661.75 m          Flash 21.0.0.216

IE 11.0.9600.18282                   Flash 21.0.0.213

Firefox 45.0.2                            Flash 21.0.0.213

FlashDevelop using Flex + AIR sdk (4.6.0 + 21.0.0)

The GameInput class, and subsequent objects and classes, are giving different results in each browser, with only Chrome functioning as I expect it to.

I'm testing http://sta.sh/088zx7tsaj2 and using the debug field I created to test how inputs are being read.

In Chrome, as mentioned, it works as intended: The swf loads, the input class starts setup, first button press occurs, and things continue.

In IE, the GameInput.DEVICE_ADDED event fires every frame, and while it says one device is available, does not detect inputs.

In Firefox, the DEVICE_ADDED event doesn't fire at all, and detects no devices added.

At this point, I don't know if its me, my computer, my lack of knowledge with setting up and using FlashDevelop, or if nobody has tried any SWF-based usb device game input stuff in four full versions.