OneDrive is the problem. See the following.
I have the same issue that also began on March 20, 2024. I have a lead but not a complete solution. First here's what I did that did NOT work: First Word > Advanced > Options > changed number of files to appear in recent list. Second, ran Microsoft Quick Repair. Third, ran Microsoft Online repair which reinstalled 365.
Here's what did work briefly: I Unlinked OneDrive. (there is a button in the OneDrive icon to do this). After this I rebooted and the full recent list DID APPEAR in Word. However it did not appear in Excel. I rebooted again and the recent list in Word disappeared again.
Conclusion: ONEDRIVE IS THE PROBLEM.
I have not yet uninstalled OneDrive but suspect this might be the full solution.
Thanks for that info, hopefully it leads closer to solution.
I am going to try your approach tonight, hopefully the recent/pinned show up so at least I can save them.