How to re-enable the "Expand to Open Folder" option?

I can say this works in the narrow context as it was described, IF you remember to click on the shortcut BUT I am not sure this is going to work in cases where no Explorer windows/tabs are opened and you click upon something which results in Explorer loading, such as the downloads icon in most browsers which will open an instance of Explorer at the specific path where that browser is configured as its default downloads path.

So, this is more of a partial workaround rather than a complete fix. I am running Windows 11 Enterprise 23H2 for work and also have Dropbox, iCloud, and OneDrive adding their extensions onto the directory trees, as well as WSL2 running an Ubuntu 22.04 image. While I get that there are a lot more moving parts I have loaded which the file system has to deal with to mount these various services at certain virtual paths along the tree, this "Expand to Open Folder" is basic Explorer functionality which I believe has worked since Windows95, if not Windows for Workgroups 3.11, which is how long I have been running some flavor of Windows (>30 years), desktop and Server.

Any explanation that this is intended behavior, or even a deprecation of how this feature has formerly worked, is not going to be met with anything other than contempt as the options are very clearly in the same place they have been for decades and they just no longer work as intended without going through one of the community-offered workarounds, of those which actually even work for any other than the one who posted those (appreciated as these contributions are, they are not universally applicable). I suppose the next logical step I could take would be to replace all instances in settings which result in Explorer launching instead with my new shortcut to Explorer with the %userprofile% argument which I created on my desktop, although I am NOT doing that as it seems like an even greater opportunity for me to break so much more functionality that I don't as readily understand.

After grousing about it for a half minute, I modified my process to include Ctrl-Shift-E to expand a single master folder. This happens to work really well for me as it's a key combination I use constantly to save files in GIMP. IOW, I have something that works for me by adding one incredibly familiar step, and I no longer care. ¯\_(ツ)_/¯

But MS is rude and disrespectful for the very reasons you laid out: People have spent a lifetime doing things one way, and with zero warning or explanation, that process, which is ridiculously benign but incredibly useful, winds up on the cutting room floor. No acknowledgment that anything has happened or that anyone was inconvenienced. But it's par for the course. Fortunately for them, MS has been showing up in urine samples for so long that it's beyond an addiction. It's a way of life.

And yet, it's funny how quickly and easily even big corporates can change to alternatives overnight when MS cuts them off due to sanctions. We can easily change to alternatives if push comes to shove; we're just spoiled and in a comfort zone, but MS is ruining the comfort zone and it's approaching a shove.

I completely agree with you that these are just workarounds and MS should fix Explorer.

But I think they will not do it in short time, so some workarounds and changes in working habit is better then to be angry each time the folders don't expand as expected :-)

Within an open Explorer window, if I start navigating the hierarchy by clicking "This PC", then "Windows (C:)" in the left frame, that sets something in windows that "turns on" the "Expand to open folder" functionality. After that I can navigate via my "pinned in Quick Access" folders and Windows will keep the left pane.