It seems like the C++ / Unreal subsystem code is creating multiple instances. A Default and "0" version of UNimForUEEngineSubsystem, and the Default is calling Tick without Initialize. The "0" version is calling Initialize(), then Default calls Tick(), then "0" calls Tick(). Why wouldn't calling NimMain in the "0"'s Initialize() work?
Oh well, I have a workaround...
