On my MacBook Pro, when I try to sign in through System Preferences, and after inserting my Apple ID and Password, iCloud goes no further. Just stays in the sign-in box. I changed my password, reset it to my computer, iPhone, iTunes and still does not work. When I go into the iCloud website and sign in, it is successful, but only shows my iPhone under the devices. Since updating to Mojave, I have lost all my bookmarks and reading list, which I had many websites saved with valuable materials, I cannot retrieve any of them because I cannot get my Mac to show up under iCloud devices, if doing this would even rectify the issue. Certainly dislike all these updates, they are very dysfunctional to say the least.