I had to wipe and reinstall to correct errors and the system now seems to work ok, except this one carryover.
The panel looks different than in screenshots: I have a mint logo, window icon, then open apps, a networking icon, sound and digital clock. Nothing else. Under the first installation, I sometimes had a full panel with a Menu icon and the word menu, and icons for all kinds of things (notifications, etc). I tried adjusting preferences, and applets for these things are all checked, but there is nothing there. Any ideas?