IRC, the main redux.dol was causing a freeze at the loading screen of the very first intro movie. So one could not even reach the first save point to register a save file and thus enabling the Redux features upon reset.
In post #359 I made this summer, I didn't mention the prerequisite of having a save file, but I now think it was the key to make it work.
The freeze on the first intro movie back then was when I didn't exactly knew how to create SFDs so they worked properly with the game, since I did struggle with movie glitches and freezes with cutscenes I specifically modified for Redux.
I have since fixed that and standardized the SFD creation process, alongside the AIX audio too, so that might have been the problem with that specific screen.