I'm using PSE 15 on a Macbook Pro Retina running Catalina, 10.15.3; (20161208.m.100202) x64. Under "Preferences>Saving Files>Recent file list contains 20 files".....but the files shown are not the most recent.
Problem started last week, recent edits no longer show up in File>Open recently edited file. There are entries from 2 weeks ago but nothing newer. As far as I know there have not been any OS updates.