Narrowed it down somewhat but it's still very odd.
Basically, the function does not crash my application if I call it before my QMainWindow object is instantiated.

Anytime after instantiating the QMainWindow object, and from anywhere in the application, the function will crash (even when the QMainWindow object goes out of scope).

That doesn't help much because the critical path (99% of my executed code) is executed via QMainWindow.

I think I'm going to need to rewrite my app bit-by-bit to discover what the root cause is