The problem is that I would need to be able to reproduce why it isn't working for you and for someone else because if it works perfectly fine on my end even with your savegame I have no idea where to look at honestly.
The last thing you can try is verify your game cache on steam and start a new game and see if the GM works there and report back.
I've just tested to check cache integrity, new game, go to red prince to test, but nothing 😭
I notice GM mode has now been removed from the readme with the latest patch (3.0.158.595 has it vs 3.0.158.595+ which doesn't). Is there any expectation that the feature will be coming back?
Thanks,
Pro
Unlikely as it caused some trouble for members which couldn't be reproduced on our side.