This issue is NOT specific to Shadow gaming; however, it will potentially impact macOS Shadow users.
The goal of this post is to collaborate, and gather information about it.
When using an XBO controller connected via Bluetooth with a Mac computer, there is the potential for “mismatched controls,” seemingly dependent on the firmware version of the XBO controller. Specifically, a subset of both the right trigger and right analog stick functions “overlap,” completely breaking functionality.
One example: run Steam in Big Picture Mode (on your Mac), then go to Settings - Controller Settings - Xbox One Controller (under Detected Controllers) - Calibrate. Then, slowly squeeze the right trigger, and notice how the "right stick" is moving on the Y axis. And if you move the right stick up and down, it moves on the X axis. The left/right triggers are supposed to only move the Z axis, whereas the right stick is supposed to only move the X and Y rotation.
The controller functionality (or lack thereof) can also be handily tested by using this web utility: http://html5gamepad.com (this site seems to work best in Chrome).
In my case, I’m able to reproduce the problem on two different MBP laptops, both running macOS Catalina 10.15.5, with two different XBO controllers, both with firmware version 4.8.1923.0.
If your BT-connected XBO controller is working fine under macOS, do not update your controller firmware! This would need to be done from an actual XBOX console, or a PC - so if you’re not using your controllers with those, they won’t get updated. Additionally, once the controller firmware has been updated, there is no going back (no downgrades)!
I created an Apple community post for this at https://discussions.apple.com/thread/251392459