Did this ever get picked up. Or was it not reproducible ?

I'm wondering if this really still exists. I cannot reproduce.

class CfgUserActions
{
	class AIM_myUserActionKey // This class name is used for internal representation and also for the inputAction command.
	{
		displayName = "My Test Action";
		tooltip = "This action is for testing.";
		onActivate = "systemchat 'activated'";		// _this is always true.
		onDeactivate = "systemchat 'deactivated'";		// _this is always false.
		onAnalog = "";	// _this is the scalar analog value.
		analogChangeThreshold = 0.1; // Minimum change required to trigger the onAnalog EH (default: 0.01).
	};
};

I use this.
Bind it to left shift (the move camera fast button for eden)
then I test in eden, I get the eventhandlers posting the systemChat's, but fast camera movement still works just fine.

I can also just bind it to "W" and it will still activate AND move the camera.

Also when I then start playing, W prints the systemChat messages and lets my character walk.
So yes indeed no repro?

Aha! Can repro if I set it to SHIFT+W, but not if I make it just shift or just W

Its generally key combo's.
If you press a combo with modded keybindings, the game blocks the main key, so CTRL+W, SHIFT+W, ALT+W , while held, will block all actions that only have W key assigned.