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

Same here :(

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.

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 :-)

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.

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.