Thank you for putting together this patch!
It seems to work as a workaround for avoiding the editor crash that i am getting in 4.18.3 when trying to work with 2 motion controllers and 4 vive trackers.
( See my bug report under: Unreal 4.18.3 - Editor crashes when turning on 6th tracked SteamVR device - Platform & Builds - Epic Developer Community Forums )
However, if i run a ( development ) build of the project, it still crashes on turning on the 6th lighthouse tracked device, with the following error:
Assertion failed: Key.IsValid() [File:D:\Build++UE4+Release-4.18+Compile\Sync\Engine\Source\Runtime\Slate\Private\Framework\Application\SlateApplication.cpp] [Line: 6103]
Is this known/expected? Does the patch only fix the Editor crash, or is it supposed to also prevent the too-many-vive-trackers crash in a build version, too?