I have the same problem. It began yesterday, 03/20/2024.
Previously, for over a year, when I opened Word it would show a list of recently opened files.
Starting yesterday, only two files showed up, and they were older files.
I can still open my docx files when I select them from File Manager, but no matter what I do they are not saved in the recently opened file list, so I can't ever open them from inside Word. I tried the suggestions about changing the number in Advanced Options, but that does nothing.
If this is a known problem, the engineers should at least tell people that, and stop presenting a "fix" that does not fix anything. It is only an inconvenience for me, because all the files I normally work on are in a few directories that I have memorized, but I can see that it is a serious problem for others.
Clearly this bug is in a very specific area of code dealing with the updating of the recently opened files. It shouldn't be so hard to fix, unless the developers are using the same code all over MS Office and are afraid to change anything. That is the design problem with making everything interdependence. You paint yourself into a corner when it comes to maintenance.