I think you have hit the core of this topic: I can’t access that page and some text claims that I have not the permit to access that page.
I only have Elementor, Loginizer and Yoast active and deactivating them does nothing.
I am not very practical with FTP but I’ll do my best to dig even there! I’d appreciate if you could provide some more specific directives to do so and anyway thank you so much, you are the first person to seriously take my case!