I have W11 on 2 computers, a Lenovo Notebook and a Dell PC with a second monitor. On both configurations the autohide issue has past away long ago, everything works fine. The autohide doesn't work, if on any of the open windows is a notification, appointements or new messages. Just confirm the notification and/or look at the window (f.e. Signal Desktop) and the autohide works fine again.
I don't want to defend Microsoft for not resolving the issue (for god's sake!!!), but I can imagine, that it is quite difficult to find the mistake, as on many configuration it works, on others not. And I cannot imagine whether they have enough informations about each of the computers with or without the problems