CommonUI Analog Cursor + Enhanced Input triggers cause triggers to get stuck when alt-tabbing

Came out of [Link Removed] and is related to this one too

I think that this is signaling that we need better solutions for input consumption in the engine honestly. This is a constant pain point within FN as well, and a large source of input related bugs I feel like. It is incredibly difficult to get Common UI + Enhanced Input to behave as expected out of the box for people, even internally

Their current workaround, quoted from UDN: 

FYI: we've work around it by spoofing "FCommonAnalogCursor::IsGameViewportInFocusPathWithoutCapture" to always return false. But this is a hack and it requires modifying the engine so this is not a proper long term solution. We're not confident that this isn't going to cause more problems later on.

Project Setup

1. Enable CommonUI
2. Set CommonGameViewport as the game viewport class
3. Create a PlayerController blueprint
   1. on BeginEvent trigger "Set Focus to Game Viewport"
   2. assign the new player controller to the thirdperson game mode
4. Duplicate IA_Jump to create a new input action IA_JumpAlt
5. Modify IMC_Default to bind "left mouse click" to IA_JumpAlt
6. Modify BP_ThirdPersonCharacter to handle Ia_JumpAlt
7. Add Print string nodes on input action handlers to distinguish which input action triggered

Bug repro

1. Enable "Game Gets Mouse Control" in the editor preferences.
2. Enter a PIE session
3. Run the command "showdebug EnhancedInput"
4. Jump with Gamepad_FaceButton_Bottom, notice it behaves properly
5. Alt-tab away from the editor
6. Alt-tab back into the editor (do not click anywhere)
7. Press Gamepad_FaceButton_Bottom repeatedly
8. Observe that IA_AltJump is stuck as ongoing in the debug display