iCloud Keychain will not sync (MacOS will not let me disable iCloud Keychain or sign out)

I know this is a commonly asked question, but none of the provided answers help me. I just installed a new computer, restored it from a backup of my old one. Everything seemed to work fine, but the iCloud Keychain was empty. After a while I had around 300 of my 1000 password items but then everything stopped, I've been waiting hours and nothing is happening, I restarted my new computer about 5 times just in case. The problem is that the 2 ways of fixing this are non-applicable. It's either 1. disable iCloud Keychain on the computer with all the passwords, wait a few minutes and then enable it again. Or 2. Sign out from iCloud on the new device, wait a few minutes and then sign in again. The problem is that both of those actions are impossible. In 1. I simply can't disable it. I try, I get all the dialogs, and then the checkmark disappears, however less than 2 seconds later it appears again. Same issue with 2. (on any computer), I try to sign out, get all the dialogs, it looks like something is happening, and then I'm signed in again. Passwords are still not syncing and I don't know what to do...