Ah - my apologies then.... Sometimes members post and then very quickly decide to delete their post (in this case probably because it didn't make sense, as you say). The notification emails still get sent out to thread contributors but by the time they take a look at the thread the post has already gone. Sorry for my misunderstanding on what I saw, or rather, didn't see....
As I said, I've never had problems accessing those settings and possibly it has been caused by a firmware update, or maybe not. Maybe someone more knowledgeable about the problem than I or someone who has experienced similar will be along to help you soon.
Meanwhile it could be worth using a search here (magnifying glass, top right) with various keywords to see if you can find anything related. I've found this one, although admittedly relating to a P4.
Trouble editing settings in app