It's great that you worked this out.
I am going to guess what happened, and it is a little convoluted.
MacOS is, by definition, a Multiple-User system. There really is no "owner" account, just Accounts with Admin Privileges (like the first or only account) and accounts with no Admin Privileges. If you choose to create only one User Account, MacOS responds exactly the same as if you had created a dozen User Accounts.
when you open a pane like Users&Groups, it COULD show you a dozen User Accounts. [and this is the source of the 'issue'.]
From there, if you only hover over the pane WITHOUT clicking on an account to specify WHICH account, it does not respond, because you have not yet selected any Account to examine/change.
The moment you click on an Account, you have specified which of the (presumed) dozen accounts you wish to examine/change, and all perks up and operates as the Mathematical Thinkers who wrote those articles expected it to. Once an account is selected by clicking, when you hover over, it responds.