It would appear that changing back to Win64 build still hasn’t fixed the issue. I now have a working version in a basic form in a new project so that I have an actor spawned from the game mode’s begin play function that contains an instanced component with an instanced UObject with an int32 that I can access successfully. Running the same scenario in my actual project doesn’t work.
In my actual project, I can’t spawn an actor from my game mode’s begin play, but I can spawn one from my player controller’s begin play. That actor then receives no components unless they are attached via a Blueprint Components panel in a derived Blueprint class. Even then, the UObject instances inside the components are never successfully maintained.
So, to be clear, the functions I call give me an instance for both CreateDefaultSubobject and NewObject, but the references don’t last (at least, I can confirm that components’ tick event still triggers). I attempted 's suggestion, but apparently the AddComponent function is deprecated and is only used internally by the Blueprint system itself now. So that doesn’t work.