i have the same issue, did you ever find a fix?
I'm updated to Win 11 Pro 24H2, and AFAICS, the problem still exists.
But I don't see the problem anymore because I'm using ExplorerPatcher: https://github.com/valinet/ExplorerPatcher
Since I upgraded to Windows 11, I've been using this app to change my Taskbar to look like Windows 10.
But 24H2 makes in impossible for ExplorerPatcher to make all the tweaks to the Taskbar that it did before 24H2, so I believe that the developers had to completely REPLACE the Taskbar with their own implementation to get it to look like Windows 10. (You can read more on the Github Project pages at the link above.) The great thing is, this implementation can give you a Taskbar where Auto-Hide works.
With 24H2, I set the ExplorerPatcher Taskbar style to the new "Windows 10 (ExplorerPatcher)" style.
The app's implementation of the Windows 10 Taskbar does have bugs. The Taskbar on my main monitor does not auto-hide unless I move my cursor over an open window or if I click on the desktop. But that's better than it not hiding at all. (I have reported this problem.)
NOTE that 24H2 Windows Defender (and some other anti-virus apps) flags ExplorerPatcher. The Github pages discuss this and tell you how to deal with it.