I’m having the exact same problem as the OP in the official adobe forum post here.
Through the link, the OP solves his problem supposedly by overriding the initialize() function. Why he does this and how it helps is still a mystery to me because I haven’t even been able to override it myself because when I try it gives me a "1021: Duplicate function definition" error.
Should I even be attempting this override? I’d like to solve my original problem which was my SystemManager null issue w/o it if possible.
As it turns out this was a result of attempting the load the module again without unloading it first. Added a remove listener that would unload the module. No issues since.