So, I have tried playing around with StructBoxLibrary but I cannot get that to work with nativizeBlueprint (now testing with 4.15.0) so it seems that plugin is broken as well.
I have also tried messing around with the P_NATIVE_BEGIN; and P_NATIVE_END; but it does not help. I still get it to run as it should, but not nativize properly I’m afraid.
Edit: What seems to happen is that nativization replaces the custom thunk with the code declared in the FCustomThunkTemplates struct. But that struct is defined in the engine so we, that do not want to make changes to the engine, can never create custom thunks and run nativization.
Can I get a confirmation on my theory and if that is the case, would it be possible to redesign to allow for customization (as I was thinking of building a plugin for http communication and it would be an annoying for everyone using the plugin to have to disable nativization for this files)?