No access to data from Icloud with advanced data protection

Like many people, I'm not able to access my files through iCloud on my browser after turning on advanced data protection. I get a popup on my phone telling me access has been granted but it doesn't work and I get a message on my browser telling me it's not got access.

From reading other forum posts it seems like this has been broken for years now and apple can't be bothered to fix this problem. Didn't they have an ad campaign a few years ago that went something along the lines of "it just works"? What a joke that turned out to be!

[Edited by Moderator]